If you ask the majority of divers to define technical diving you will probably end up with a definition at least partly based on depth.

Koh Tao, Thailand

Although the ability to dive deeper than recreational limits has always been one of the major aspects of technical diving it is by no means the only aspect. Technical diving is about extending your diving and this extension can develop along a number of different dimensions.

One of the biggest advantages to using technical diving techniques is in extending the length of the dive rather than the depth. For example a recreational diver with a Deep Diver specialty is certified to dive to 40m. However, 40m recreational dives don’t make a lot of sense. The no stop limit for 40m is between 8 and 10 minutes depending on the tables you use. If you have spent three hours driving to the coast and another two hours on a boat to get out to a wreck then that is a round trip time of ten hours for a ten minute bottom time. That’s an hour traveling time for every minute on the wreck. Similarly if we add up the cost of the fuel for the drive, cylinder fills for the dive, charter fee for the day, possibly overnight accommodation and all the other costs then it results in a huge cost for each minute spent on the wreck.

Of course that ten minutes also includes the descent time so we often end up spending only five minutes on the wreck itself. If the tide is running or you are dropped on a part of the wreck where there are no interesting features then this can be reduced even further. If we know that we only have a few minutes on the wreck then we tend to rush more and as a result may miss interesting points. The temptation to rush the descent in order to get more time on the wreck combined with the overall time pressure also increases the risk of nitrogen narcosis. Thinking back to my own experience of 40m no stop dives I can remember lots of enthusiasm and excitement before the dive followed by a feeling after-wards that the dive didn’t quite live up to expectations. I always felt that I hadn’t really seen the wreck and had no feel for how it was lying and the structure of the wreck. There was always a feeling that although that dive was a bit of a disappointment the next dive would be better and I would get a better view of the wreck next time. On those dives where we were lucky and had fantastic visibility there was a huge feeling of regret that we couldn’t stay longer on the wreck.

Technical diving and specifically decompression diving offers the possibility of significantly increasing the time you can spend on the wreck with only marginal increases in cost, effort or risk. Once you are properly equipped and trained for decompression diving then the no stop time disappears as a limitation of your diving. If you are prepared to undertake a certain amount of decompression stops on the ascent then you can pass that no stop time and enjoy a significantly increased time on the bottom. For example, if we increase our bottom time from ten minutes to 20 minutes then we in effect more than double our actual time on the wreck as the descent time stays the same. This means that we are getting more than twice as much time on the wreck for the same cost, the same travelling time and almost the same effort. This extra ten minutes will give us much more time to explore the wreck and get a feel for the layout. We can certainly see more of a wreck in a single 20-minute dive than we will in two ten-minute dives. Now the price of this extra time is that we will have to perform decompression stops on the way back to the surface. In this case a 20-minute bottom time will give us 11 minutes of decompression stops. This seems to be well worth the effort. An additional 11 minutes of decompression at the end of the dive doesn’t seem to be an unreasonable cost to pay for the increased time on the bottom. After all getting time on the bottom is why we dive.

As we increase the time on the bottom the amount of decompression also increases. If we do a 30-minute bottom time then we will have to do 30 minutes of decompression on the way back up. While 30 minutes on a wreck is very appealing, 30 minutes of decompression is now starting to become a significant price to pay. For many divers 30 minutes of decompression is a significant amount and they start to think that the benefit to cost relationship is starting to swing too far towards the cost. In addition, as the decompression obligation increases the gas reserves that are required start to increase. However there are additional ways that technical diving techniques can start to help.

The above examples were all worked out assuming that the diver is breathing air. However, by changing our breathing gas we can gain a further advantage. For no stop dives at 40m the advantage of nitrox is minimal. The risk of oxygen toxicity means that we can only use relatively weak nitrox mixtures which have a minimal effect on no stop times. Using EAN28 at 40m increases our no stop time from eight minutes to 12 minutes. Although this is a 50 per cent increase the additional cost of a nitrox fill for four minutes extra on the bottom is often judged to be not worth it. However, for decompression dives the advantage becomes more noticeable. In the example above, a dive to 40m for a bottom time of 30 minutes resulted in 30 minutes of decompression if we are breathing air. On the other hand the same dive, using EAN28 rather than air, gives only 17 minutes of decompression.

Although this is less than the 50 per cent advantage on the no stop dive a saving of 13 minutes is much more noticeable and is often considered to be well worth the cost and effort of using nitrox rather than air. We have already established that we can see more of the wreck in a single 20-minute dive than in two ten-minute dives and this principle is even more applicable for a 30-minute dive. We have the time to properly explore the wreck, to investigate certain areas in detail and even to start to penetrate into the interior of the wreck. We can often swim the length of a wreck and see the bigger picture of the shape, condition and layout of the wreck. It’s not until you start to do longer dives on a 40m wreck that you can even start to get an overall feel for the wreck and really start to get to know it. For wreck researchers this length of bottom time is very valuable in providing time to be able to start identifying features and begin the process of identification.

In addition to using nitrox as our main breathing gas, technical diving techniques also allow us to switch to a second nitrox mix during the decompression in order to further optimise our decompression. Decompression stops allow time for dissolved nitrogen to come out of the body. We cannot ascend any higher until a certain amount of nitrogen has been allowed to escape. If we do ascend before the required amount of nitrogen has been allowed to escape then it will form bubbles which is the cause of decompression sickness (DCI). When we switch to a second nitrox mixture with a higher percentage of oxygen, and by implication a lower percentage of nitrogen, the nitrogen dissolved in our body comes out faster and so we don’t need to wait as long before we can move up in the water. This is why the technique is known as accelerated decompression, although some people prefer the term optimised decompression.

By using EAN50 as a decompression gas we can reduce our decompression to 13 minutes and by using EAN80 or even 100 per cent oxygen we can reduce it to just nine minutes. Alternatively we could further increase our bottom time to 35 or even 40 minutes until we reached the maximum amount of decompression time we were happy to do. Of course you don’t get anything for free and using this technique introduces a number of other considerations that the diver will need to take into account. In particular, much more detailed gas planning and the risk of oxygen toxicity must be considered. This is why specialised training is required in order to make use of these specific tools. In particular the decompression times and dive practices contained in these examples should not be taken as correct and are only provided for illustration (that should keep the lawyers happy).

It should now be starting to become clear why some qualifications limit the time as well as the depth of the dive. There is only so much trouble you can get into on a no stop dive whereas there is more potential for problems on a decompression dive. Recreational dive qualifications limit divers to no stop times to limit the risks they are exposed to. Some other courses limit the diver to 15 minutes of decompression and are sometimes referred to as advanced recreational courses rather than full technical courses. As the diver progresses to full technical courses then the skills they will learn and the planning techniques they will use means that there is no limit on the amount of decompression a diver can carry out as long as they stay within the safe limits of gas availability, CNS and all other planning variables. In many cases it will be the diver’s own personal limits rather than any external factor that determines the maximum amount of decompression they want to do.

The skills contained within technical diving courses that allow a diver to extend the time they can spend on the wreck are also a way to extend your diving. Many people undertake this training so that they can be safer and more skilled at the depths they are currently diving at rather than to progress any deeper. The skills required for technical diving can also make you a significantly better recreational diver. Having better buoyancy control, awareness of your situation and of your buddy will all help to make you a better diver. Together with better self rescue and buddy rescue skills they will also make you a safer diver no matter what depth you are at.

One of the things that distinguish technical divers from recreational divers is the amount of equipment and, in particular, the number of cylinders that are carried.

Koh Tao, Thailand

A recreational diver might carry a single cylinder and for some dives may add on a pony cylinder for redundancy. Technical divers will use either a twinset or a rebreather but in addition will carry a number of stage cylinders. They are usually clipped onto the diver’s side.

The term ‘stage cylinder’ is used as a generic term to describe these cylinders but in fact there are a number of different uses for which we use these cylinders and their names reflect the purpose that the cylinder is serving at the time. Another term that is used is a ‘side-slung’ or just ‘sling’ cylinder. This comes from the fact that the cylinder is usually mounted or slung on the side of the diver. The term ‘stage’ cylinder comes from cave diving, where divers would stage or drop cylinders at various points in the cave for use on the way out. So, for example, a cave diver might swim in breathing from his stage cylinder and when he has breathed a third of it he would remove it and clip it to the guideline. He would then continue using his twinset until that was also a third used. At this point he would turn around and start swimming back out. Using this method he should get back to his stage cylinder with a third still left in his twinset. At this point he would pick up his stage cylinder, which still has two thirds left and breathe that for the rest of the exit. Using this approach he will exit the cave with a third reserve in his twinset and a third reserve in his stage. This approach works as the cave diver knows that he will be exiting along the same line that he entered and so will always be returning to his stage cylinders.

This approach is normal in cave diving but is much less common with wreck penetration diving. The two reasons for this are that firstly the penetration distances in wreck dives are not usually as long as with cave dives. Secondly the number of exits may mean that we exit the wreck at a different point to the one we entered and so we may not always get back to our stages. As a result it is much less common to stage gas on wreck penetration dives. The exception to this is that some divers remove their stages before entering a narrow restriction or hole. This allows them to get into more restricted areas but should be used with caution as if they cannot get back out or have to exit in another area then they cannot easily get back to their staged gas. For this reason it is recommended that wreck penetration divers do not stage their cylinders. The most common use of stage cylinders for wreck dives or any other open sea dives is to carry a decompression gas. When used in this way stage cylinders are usually referred to as deco cylinders. In this case they will contain a rich nitrox mix which is used to accelerate or reduce the diver’s decompression obligation.

Wreck divers may also carry a stage cylinder containing the same gas as in their twinset. This is known as bottom gas as it is breathed on the bottom rather than deco gas, which is breathed on the ascent and decompression stops. A bottom gas stage might be used to extend the bottom time of the dive if the twinset doesn’t contain sufficient gas to allow a safe reserve. It can also be used where getting subsequent fills may be difficult. In this case the diver may plan to use their bottom gas stage and a proportion of their twinset on one day and then use an additional pre-prepared bottom gas stage and the rest of their twinset for the next day. In this way they can get two dives from a single twinset and two stages of bottom gas.

The last use of stage cylinders is as a bailout stage for rebreather divers. A rebreather diver would normally plan to use their rebreather for the duration of the dive. However, if there is a problem with the rebreather then the diver would ‘bailout’ to the stage cylinders he is carrying. In this case the diver would need a bailout cylinder that they could start using at the maximum depth and would then need sufficient bailout to get to the surface completing all their decompression. Unlike the open-circuit diver the rebreather diver will not use their stages unless there is an emergency but will still need to carry them.

One of the biggest dangers facing the technical diver is breathing from the wrong cylinder and, in particular, breathing a rich nitrox mix at depth which will almost certainly lead to oxygen toxicity. For this reason it is essential that all stage cylinders are analysed before use and labelled accordingly. The maximum depth at which the gas can be breathed, known as the maximum operating depth or MOD, should be clearly marked on the cylinder in a position where the divers buddy can clearly see it. The contents and date analysed should also be marked but this can be smaller and less obvious. Every time that the diver switches to a stage cylinder he must get his buddy to check that the gas is safe to breathe at that depth. This is why the depth is marked rather than the percentage of oxygen in the mixture. It is much easier to check your depth rather than look at a percentage and work out the maximum safe depth in your head.

The main choices when using a stage cylinder are the composition of the cylinder and the size. Stages can very from five litres all the way up to 12 litres. The right choice of size will depend on a number of factors. The larger the capacity the larger the physical dimension and weight of the cylinder, and so the diver needs to consider what size cylinder they are happy to carry, both on the surface and on the bottom. The choice of decompression gas will also have an impact on the size of cylinder required. For example, if a diver uses 50 per cent for their decompression gas then they will switch to it at 21m and breathe from this cylinder for the majority of their decompression, as a result they will need a large volume of decompression gas and will need a larger cylinder to carry all of that gas. However, if the same diver uses 100 per cent oxygen as their decompression gas they will not switch until they get to 6m and, as a result, will use much less decompression gas and so can carry a smaller decompression cylinder. In the UK seven-litre stages are the most common, but in recent years with the increasing popularity of using 50 per cent as a decompression gas, it has become more common to see larger decompression stages. Although most UK cylinders are measured in terms of litres, some cylinders are now measured in cubic foot. 40 cubic foot and 80 cubic foot cylinders are becoming more common. 40 cf is approximately equal to a five-and-a-half-litre cylinder with 80cf cylinders containing approximately 11 litres. For divers using 50 per cent as a deco gas and requiring more volume of decompression gas, an 80 cf cylinder is an attractive option.

With a single stage cylinder it is common to wear this on the left-hand side. Typically the top of the stage cylinder is clipped to the D-ring on the left hand shoulder with the bottom clipped to a waist D-ring on the left-hand hip. However, when using multiple stages, either because of using multiple decompression gases, using a bottom gas stage together with a decompression stage or with multiple bailout cylinders while diving a rebreather, we need to consider where we will carry the cylinder. One option is to carry two or more cylinders all on the left-hand side. The other option is to clip one cylinder on the left and one on the right. In this case the leanest mix, the one with the lowest percentage of oxygen, is worn on the left-hand side and the richest mix, with the highest percentage of oxygen, is worn on the right-hand side. For this reason this approach is known as lean left – rich right. The best option, all stages left or lean left - rich right, will depend on a number of factors. For example if the diver is using steel stages, then the fact that they will be very negatively buoyant will make wearing them both on the left very uncomfortable as they will pull the diver over to that side. In this case wearing them lean left – rich right will be much more balanced. However if the diver is using aluminium stages then having them on the same side is perfectly feasible and can be more comfortable.

As the number of stages increases the decisions get more complicated. With three stages it is still possible to wear them all on the left hand side whereas with lean left – rich right you will need to have two stages on one side and one on the other. With four stages it is no longer possible to have them all on the same side although it is possible to have two on the left and two on the right. Beyond this additional solutions have to be used, either stages staged on the shot line, support divers carrying additional stages for use on the later parts of the decompression or the use of a leash to attach additional cylinders behind the diver. Neither of these options are desirable for open water diving. Using stages on the shot line or support divers mean that the diver is no longer self sufficient and adds significantly to the complexity and organisation required for the dive. In addition there is always the risk that the diver will have to ascend away from the shotline. Multiple cylinders can be carried by the diver if they use a leash; this is a loop of rope with a boltsnap attached. Multiple stages can be attached to the leash and then the leash clipped onto the hip D-ring so that the stages trail behind the diver. This approach will only work with aluminium stages as steel stages will be negative and will not sit comfortably on the leash. In addition only certain types of aluminium cylinder, and even then only at certain pressures, will sit comfortably. The use of a leash adds an additional level of complexity and risk to open water wreck dives. For these reasons the majority of technical divers do not use more than three or four stages.

3 weeks of training brings recreational diver to the pinnacle of deep air diving.

Koh Tao, Thailand

Big Blue Tech celebrates the graduation of Etienne De Beer from his TDI Extended Range conducted over 3 days by TDI Instructor James Thornton-Allan off the coast of Thailand on Koh Tao Island.

The TDI Extended Range course is at the pinnacle of deep air diving with training and certification to 55m using multiple mixes and gasses up to pure oxygen to accelerate decompression.

Etienne came to us from South Africa with his family to take the “Tech Diver Package” which included the TDI Intro To Tech, TDI Advanced Nitrox, TDI Decompression Procedures and finally TDI Extended Range. In addition to this package Etienne received the BSAC Extended Range Diver certification when his instructor James fractured his foot and had to remain out of the water for a period of time allowing his colleague Ash Dunn to replace him.

The course taught Etienne all the qualities and skills Big Blue Tech has to offer with over 25 logged technical dives. Etienne overcame some obstacles including the backwards fin kick which he achieved on dive 19 after weeks of practice and the strength of climbing out of the water with 4 cylinders on, a weight of 100kg ( cylinders weight 14kg each before you add all the valves and regulators) which he took in stride.

We’re always proud of our students and the effort that they put in to learn and focus and this course was no exception. in the final test or challenge Etienne excelled and performed above requirements.

Technical diving (sometimes referred to as Tec diving) is a form of scuba diving that exceeds the scope of recreational diving (although the vast majority of technical divers dive for recreation and nothing else). Technical divers require advanced training, extensive experience, specialized equipment and often breathe breathing gases other than air or standard nitrox.

The concept and term ‘technical diving’ are both relatively recent advents,[note 1] although divers have been engaging in what is now commonly referred to as technical diving for decades. The term “technical diving” was first coined by Michael Menduno, editor of (now defunct) diving magazine AquaCorps in 1991.
Definition of ‘technical diving’

There is some level of professional disagreement as to what the term should encompass. It was not that many years ago that NITROX diving was considered “technical”; however today NITROX is not normally considered technical. Some say that technical diving is any type of SCUBA that is considered higher risk than conventional recreational diving. However, some advocate that this should include penetration diving (as opposed to open-water diving), whereas others contend that pentrating overhead environments should be regarded as a separate type of diving. Others seek to define technical diving solely by reference to the use of decompression. Certain minority views contend that certain non-specific higher risk factors should cause diving to be classed as technical diving. Even those who agree on the broad definitions of technical diving may disagree on the precise boundaries between technical and recreational diving.

PADI, the largest recreational diver training agency in North America, defines technical diving as “diving other than conventional commercial or recreational diving that takes divers beyond recreational diving limits. It is further defined as an activity that includes one or more of the following: diving beyond 40 meters/130 feet, required stage decompression, diving in an overhead environment beyond 130 linear feet from the surface, accelerated stage decompression and/or the use of multiple gas mixtures in a single dive.”

NOAA defines technical diving in this way: “Technical diving is a term used to describe all diving methods that exceed the limits imposed on depth and/or immersion time for recreational scuba diving. Technical diving often involves the use of special gas mixtures (other than compressed air) for breathing. The type of gas mixture used is determined either by the maximum depth planned for the dive, or by the length of time that the diver intends to spend underwater. While the recommended maximum depth for conventional scuba diving is 130 ft, technical divers may work in the range of 170 ft to 350 ft, sometimes even deeper. Technical diving almost always requires one or more mandatory decompression “stops” upon ascent, during which the diver may change breathing gas mixes at least once.” NOAA does not address issues relating to overhead environments in its definition.

The following table tries to set out the broad indicative parameters of what is normally regarded as technical rather than recreational diving.

Technical dives may be defined as being either dives to depths deeper than 130 feet / 40 meters or dives in an overhead environment with no direct access to the surface or natural light. Such environments may include fresh and saltwater caves and the interior of shipwrecks. In many cases, technical dives also include planned decompression carried out over a number of stages during a controlled ascent to the surface at the end of the dive.

The depth-based definition is derived from the fact that breathing regular air while experiencing pressures causes a progressively increasing amount of impairment due to nitrogen narcosis that normally becomes serious at depths of 100 feet / 30 metres or greater. Increasing pressure at depth also increases the risk of oxygen toxicity based on the partial pressure of oxygen in the breathing mixture. For this reason technical diving often includes the use of breathing mixtures other than air.

These factors increase the level of risk and training required for technical diving far beyond that required for recreational diving. This is a fairly conservative definition of technical diving.

Inability to ascend directly

Technical dives may alternatively be defined as dives where the diver cannot safely ascend directly to the surface either due to a mandatory decompression stop or a physical ceiling. This form of diving implies a much larger reliance on redundant equipment and training since the diver must stay underwater until it is safe to ascend or the diver has left the overhead environment.

Decompression stops

A diver at the end of a long or deep dive may need to do decompression stops to avoid decompression sickness, also known as the “bends”. Metabolically inert gases in the diver’s breathing gas, such as nitrogen and helium, are absorbed into body tissues when breathed under high pressure during the deep phase of the dive. These dissolved gases must slowly be released from body tissues by pausing or “doing stops” at various depths during the ascent to the surface. In recent years most technical divers have greatly increased the depth of the first stops, so as to reduce the risk of bubble formation before the [more traditional] long shallow stops. Most technical divers breathe enriched oxygen breathing gas mixtures such as nitrox during the beginning and ending portion of the dive. To avoid nitrogen narcosis while at maximum depth it is common to use trimix which adds a percentage of helium replacing nitrogen to the diver’s breathing mixture. Pure oxygen is then used during shallow decompression stops to reduce the time needed by the diver to effectively rid themselves most of remaining excess inert gas in their body tissues and reducing the risk of “the bends.” Surface intervals are usually required to prevent the residual nitrogen from building up to dangerous levels on subsequent dives.

Physical ceiling

These types of overhead diving can prevent the diver surfacing directly:

* Cave diving - diving into a cave system.
* Deep diving - diving into greater depths.
* Ice diving - diving under ice.
* Wreck diving - diving inside a shipwreck.

Extremely Limited Visibility

Technical dives in waters where the diver’s vision is severely impeded by low-light conditions, caused by silt or depth, require an elevated level of aptitude because of the knowledge and skill required to operate in such an environment, and because visibility impairments are often caused by moving water currents. The combination of low visibility and swift current make these technical dives extremely risky to all but the most skilled and well-equipped divers.[citation needed]

Gas mixes

Technical dives may also be defined by the use of hypoxic breathing gas mixtures other than air such as trimix, heliox, and heliair. This definition is derived from the fact that breathing a mixture with the same oxygen concentration as is found in air (roughly 21%) at depths greater than 180 feet / 55 meters results in a very rapidly increasing risk of severe symptoms of oxygen toxicity. The first sign of oxygen toxicity is usually a convulsion without warning. This convulsion usually results in a fatal accident, as the regulator falls out and the victim drowns. Sometimes the victim may get warning symptoms prior to the convulsion. These can include visual and auditory hallucinations, nausea, twitching (especially in the face and hands), irritibility and mood swings and dizziness. Increasing pressure due to depth also causes nitrogen to become narcotic, resulting in a reduced ability to react or think clearly (see Nitrogen narcosis). By adding helium to the breathing mix, divers can reduce these effects, as helium does not have the same narcotic properties at depth. These gas mixes can also lower the level of oxygen in the mix to reduce the danger of oxygen toxicity. Once the oxygen is reduced below 18% the mix is known as a hypoxic mix as it doesn’t contain enough oxygen to be used safely at the surface.

Nitrox is another common gas mix, and while it is not used for deep diving, it decreases the build up of nitrogen within the diver’s body by increasing the percentage of oxygen. This reduces the nitrogen percentage, as well as allowing for a greater number of multiple dives vs “standard” air. The depth limit of Nitrox is governed by the percentage of oxygen used, as there are multiple oxygen percentages available in nitrox. Further training and knowledge is required in order to safely use and understand the effects of these gases on the body in a diving situation.

“Deep air”/extended range diving

One of more divisive subjects in technical diving relates to using compressed air as a breathing gas on dives below 130 feet/40 meters. Whilst the largest technical diver training agencies still promote and teach such courses (TDI, IANTD and DSAT/PADI), there is an increasingly vocal minority (NAUI Tec, GUE, UTD) which argues that diving deeper on air is unacceptably risky, and argue that helium mixes should be used for dives beyond a certain limit (100 - 130 feet, depending upon agency). Such courses used to be referred to as “deep air” courses, but are now commonly called “extended range” courses.

Deep air proponents base the proper depth limit of air diving upon the risk of oxygen toxicity. Accordingly, they view the limit as being the depth at which partial pressure of oxygen reaches 1.4 ATA (which occurs at about 186 feet/50 metres). Helitrox/triox proponents argue that the defining risk should be nitrogen narcosis, and suggest that when the partial pressure of nitrogen reaches approximately 4.0 ATA (which occurs at about 125 feet/38 meters) helium is necessary to offset the effects of the narcosis.

DAN does not formally reject deep air diving per se, but it is keen to point out a number of additional risks which such diving involves.

Equipment

Technical divers may also use various forms of less common diving equipment to accomplish their goals. Typically technical dives involve significantly longer durations than average recreational scuba dives. As decompression stops act as a virtual overhead, preventing a diver with a problem from surfacing immediately, there is a need for redundant equipment. Technical divers usually carry at least two tanks, each with its own regulator. In the event of a failure, the second tank and regulator acts as a back-up system. Technical divers therefore increase their supply of available breathing gas by either connecting multiple high capacity diving cylinders and/or by using a rebreather. The technical diver may also carry additional cylinders, known as stage bottles, to ensure adequate breathing gas supply for decompression with a reserve for bail-out in case of failure of their primary breathing gas. The stage cylinders are normally carried using an adaptation of a sidemount configuration.

Training

Technical diving requires specialised equipment and training. There are many technical training organisations: see the Technical Diving section of List of diver training organizations. Technical Diving International (TDI), Global Underwater Explorers (GUE), International Association of Nitrox and Technical Divers (IANTD) and National Association of Underwater Instructors (NAUI) seem to be popular as of 2009. Recent entries into the market include Unified Team Diving (UTD), and Diving Science and Technology (DSAT), the technical arm of Professional Association of Diving Instructors (PADI). The Scuba Schools International (SSI) Technical Diving Program (TechXR - Technical eXtended Range) was launched in 2005.

British Sub-Aqua Club (BSAC) training has always had a technical element to its higher qualifications, however it has recently begun to introduce more technical level Skill Development Courses into all its training schemes, by introducing technical awareness into its lowest level qualification of Ocean Diver, for example, nitrox will become mandatory. It has also recently introduced trimix qualifications and continues to develop closed circuit training.

A recreational diver who explored the seabed off Shag Harbour, N.S., where a UFO is alleged to have crashed in 1967, says what he saw last month can’t be explained.

David Cvet and a diving buddy came across a couple of dish-shaped depressions, each about six metres in diameter. The ocean bottom anomalies were found 11 fathoms, or about 20 metres, below the surface, in the spot where witnesses say an alien craft swooshed low over the Shelburne County coast.

“In the depression itself, it was as if somebody had come by the day before and swept it clean,” said Cvet on Friday during the Shag Harbour UFO Incident Society’s second annual festival and symposium.

He said the depression was lined with pebbles about four to six centimetres in size. The surrounding seabed had large rocks and pebbles and vegetation.

On Oct. 4, 1967, several witnesses described seeing something crash into the sea off Shag Harbour. In fact, people as far away as Yarmouth, N.S., reported seeing something streak across the night sky.

There were no reports of aircraft in trouble that evening, even though a patch of yellow foam about seven centimetres thick was seen on the water off Shag Harbour not long afterwards. The incident has been listed as a UFO crash.

Cvet, who’s from Toronto but summers in Smith’s Cove, N.S., said he’s known about the Shag Harbour UFO incident for many years.

“I think (it) has enough compelling evidence to warrant further investigation,” he said.

On July 20, Cvet used a copy of a 1988 report from a bottom sonar sweep of the area that found four dish-shaped anomalies.

He and a friend worked out the co-ordinates and planned their dive.

“We left from Lower Woods Harbour and came down to this location and dropped a buoy overboard,” he said, tracing the boat’s 25-minute trip on a map with his finger.

The divers entered the water just before 2 p.m., about 10 minutes before low tide. It was a pleasant 24 degrees on the surface and about 16 degrees at the bottom.

“The water was pretty much like pea soup,” Cvet recalled.

Nevertheless, they soon came upon the first of two depressions.

They came, they saw, they didn’t quite break the record.

About 13 Lorain County residents were part of a massive effort Saturday at Gilboa Quarry near Findlay to break the Guinness world record for most divers submerged at one time. Only 794 people participated, short of the 958 people who submerged themselves for 20 minutes underwater in 2006 off the cost of the Maldives islands in the Indian Ocean.

The event drew people from all over the country and Canada, and even though the record wasn’t broken this time, plans to bring the record to the United States and Ohio are in the works for next year.

“We’re bound and determined to break this,” said Jim Blauvelt, of Elyria, who was one of about 100 people who already signed up to dive next year at the quarry. “Even though we didn’t this year, we tried, and it will fall.”

794 divers participated in a world-record attempt Saturday at Gilboa Quarry. (Photos courtesy of Jim Blauvelt.)

Blauvelt said about 150 people registered for the dive but did not show up Saturday, which would have put them within striking distance of the record. The number of people this year was better than the previous record of 722 people, also set off the Maldives, in 2005.

“They have a definitive advantage,” Blauvelt said. “Most people like warmer water to dive in, but we already had more than they had (in 2005). so we have a very good chance of breaking it next year.”

A recreational diver for the past three years, Blauvelt, 39, said the event was a blast despite not getting enough people. It included a DJ, barbeque pulled pork, homemade ice cream, chain saw wood carvings and a social event to rival any other.

“Everyone was so personal,” said Wendy Vayda, another Elyria resident, who has been diving since 2004. “It was so much fun.”

Divers get ready Saturday at Gilboa Quarry.

Lanes were set up in the 14-acre quarry using nylon rope and down lines were there for divers to hold onto while they stayed underwater.

Blauvelt said the whole process only took about 90 minutes, from the time the divers went in the quarry, to the time they got out.

Those interested in attempting to break the record next year should visit the Gilboa Quarry Web site at www.divegilboa.com.