Dorothea: The Incident Pit

Dorothea Shallow Tunnel
Dorothea Shallow Tunnel

Last Updated on June 28, 2024 by Divernet Team

There were public calls to close Welsh inland site Dorothea Quarry at the end of last year, after three divers lost their lives there in quick succession.

Paul Kay believes the quarry's infamous image is inevitable given its combination of cold, depth – and a worrying attitude among some divers.

IF YOU VISITED DOROTHEA QUARRY SOME YEARS AGO, before diver training agencies recommended against diving this flooded quarry and the landowner attempted to stop diving here, you will know how popular it can be.

There could have been hundreds of divers visiting it each weekend.

But all good things come to an end, and diving in Dorothea is unlikely to prove an exception.

It might surprise many of the divers who visit this quarry in North Wales to discover just how bad a reputation it now has as a diver-killer.

For those of us who live here, it is becoming ever more obvious that if problems continue to occur, restrictions will finally be imposed.

Any legal restriction might have far wider implications for all sport divers.

Despite the landowner's attempts to stop diving in the quarry, and all the sport's training agencies recommending against diving in it, many divers still regard it as a viable dive site.

Although there are now supposedly fewer divers using it, there are still many incidents.

So why does Dorothea have so many problems?

Well, as no records exist of the actual numbers of divers who have used and continue to use Dorothea, nor of all the incidents, it is difficult to tell whether the incident rate is above average, but at the end of 2001 three diving deaths occurred here within a month.

This is clearly unacceptable to anyone, and inevitably there have been numerous calls to halt diving at the quarry.

The Daily Post, North Wales' biggest daily newspaper, ran a front-page piece about the third death under the headline ‘Stop This Madness'.

This fatality also made the national news on both radio and television. While some reporting was both factual and objective, some was utterly sensationalist and wildly inaccurate.

A BBC reporter who stated that dangerous strong currents were a problem in the quarry clearly had little idea of what he was talking about, or from where he was talking!

These latest incidents prompted many people to call for an outright ban on diving in Dorothea. This has happened before, but local MP Hywel Williams is now seeking a meeting with the Sport Minister and eventually some controlling action is likely to be taken.

‘Sometimes regulations are necessary to protect people from endangering their own lives,' he is quoted as saying.

Local councillor Les Williams agrees: ‘I am asking that these type of activities are barred until proper facilities are on site.'

Cold and Dark

Over the years Dorothea has claimed many other divers' lives. There appears to be little absolute correlation between the deaths, and to examine them all in detail would involve immense research, but the quarry does have known problems.

Some can be minimised by proper dive planning, choice of suitable equipment and agreed and viable safety procedures. Others are more imponderable.

Essentially the most serious problems come under three headings – temperature, depth and attitude.

It can be cold in the water, and sometimes extremely cold. In winter the temperature drops as low as 3?C, both at the surface and at depth.

In summer the surface can be far warmer, at up to 15?C, but one and sometimes two thermoclines may exist, and below them the temperature plunges to near winter figures.

Cold water is a well-known problem for divers, and can be overcome by using suitable equipment. Coldwater regulators are essential.

My own, which is a top-of-the-range, environmentally sealed model – has spat ice particles at me in Dorothea, to illustrate just how bad the cold can be.

Gush of Bubbles

In winter it used to be common at the surface to see a sudden large gush of bubbles at the surface, the sign of a free-flow occurring as a first stage froze, followed by the appearance of the divers themselves.

I have brought up on my own pony air supply one diver who suffered a first-stage freeze-up.

This aspect of regulator design has fortunately improved in recent years, as has divers' knowledge of regulator free-flow problems, thanks to press articles and improved training.

It is good technique, and of course common sense, to carry a secondary, independent air supply in water as cold as that found in Dorothea.

This too should be fitted with an appropriate cold-water regulator.

It is also essential to use a drysuit in Dorothea and to wear adequate insulation. Again, undersuits and thermal underwear have improved dramatically in the past few years.

They are now highly efficient, and not horrendously expensive.

Drysuits should be in good condition and dry in use – I have watched one diver emerge from a shallow dive in Dorothea with a failed drysuit seam, and he was extremely cold, to put it mildly.

Some divers dive in Dorothea wearing borrowed, ill-fitting wetsuits. I have spoken to at least one who described herself as feeling ‘faint with the cold' after a 15 minute dive in such a suit – lunacy!

Using a wetsuit is to take a pointless risk, yet some dive schools apparently consider them to be viable for trainees in Dorothea.

Far from it – using them in such conditions might well be a breach of health and safety legislation on the part of the instructors.

The HSE confirms that ‘if any wetsuit-clad diver had an accident during training, we would look at temperature, time and depth issues; there is also the possibility of buoyancy loss to be considered.'

Lastly, I have myself aborted club diver training in the past after watching the shock register on a would-be BSAC Advanced Diver as he took his mask off during the relevant assessment during winter!

Depth is the second real problem. Dorothea is very deep – more than 100m in places. Some areas are shallow, but most of the quarry is not.

In some ways depth can be an advantage, but not in all ways.

For divers wanting to train at depth for extended-range operations, for technical and even free-diving, depth is essential.

For technical divers Dorothea is seen as an excellent training ground, but is it?

In reality it has only two real advantages over the sea; its total lack of currents and, if the access issue is finally sorted out, potentially year-round availability.

It is no lighter, often no clearer, and far colder than most deep marine sites. Whether technical training in such fresh water is a good preparation for open-sea diving is also debatable.

For others divers, depth remains a potential hazard, and especially so for the inexperienced or those under training.

Dorothea has some drop-offs that are spectacularly dramatic, or intimidating and frightening, depending on your point of view.

There is often no even progression, with depth dropping away in a series of huge steps – the underwater cliffs here can be tens of metres high.

The quarry is not a good place for anyone still struggling to achieve good buoyancy control.

Wolf in Sheep's Clothing

But the third and potentially worst problem of all is that Dorothea is a wolf in sheep's clothing, and we divers appear to be exceedingly gullible! The quarry can appear so benign.

It is after all very calm, there are no currents, it can be remarkably clear and there are often lots of divers around to help if anything untoward should happen.

Divers' psychology is an inherent part of Dorothea's problem, and Dorothea is only too capable of lulling divers into a false sense of security.

I suspect that there are few of us who have not disregarded a dive plan, gone a bit deeper than anticipated, or taken one of a myriad of the other ‘little' risks that breach recommended diving practices.

Most of the time we get away with it.

But in Dorothea there is an apparent temptation not to prepare adequately for what would usually be regarded as a ‘serious' dive, or to dramatically exceed depth limits.

Either failing can be disastrous. One professional dive instructor has told me: ‘I've heard divers discussing: ‘What do you want to do today?' as they've swum over to the buoys leading down to the ladder at 42m.'

There are also many divers who seem happy to disregard the 50m recommended sport diving limit for air completely, and by substantial amounts.

Hitting 60m is apparently far from uncommon and some divers are reported to have gone as deep as 100m using standard open-circuit scuba gear.

Some divers do this after considerable preparation and extensive studying of the problems of air-diving at this depth, but no one can be fully aware of their abilities or the consequences of any incident at such depths.

It's about as close to the limits of my abilities as I want to get,' said one very experienced diver about his deep diving in Dorothea.

It is tempting to consider that only a tiny minority undertake this sort of diving, but it wouldn't be true.

I have spoken to many divers – some very experienced and highly competent – who readily admit to such diving, though they are understandably reluctant to be named.

A story so bizarre that it surely must be true is the one about some divers who dived to 50m and then breath-held as they ‘bounced' deeper still.

This ‘technique' was adopted, apparently, to avoid oxygen poisoning!

Apart from the inherent risks such diving practices pose to them, those who dive in this way set an appalling example to other divers, as well as to a far wider audience.

This mixture of attitude, recklessness, irresponsibility and, dare I say it, stupidity, is probably Dorothea's biggest problem.

Slate Waste

If things don't change, a legally enforceable ban will surely occur and we might all suffer from the consequences of the precedent that this might set.

So what of the future? The quarry is privately owned, and the local council confirms that at present there is no legal public access to it for scuba diving.

There has been talk of developing the site as a dive centre, and a start has been attempted, but this plan is fraught with difficulties.

If it were to happen, the likelihood of incidents occurring remains, and might even rise, given that diver numbers would increase.

As a tekkie centre, the difficulties of dealing with decompression incidents are considerable. And at the end of the day, both cold and depth still exist.

Perhaps the best thing to do would be to dump some of the 6 million tons of slate waste back into the quarry and reduce its depth.

The last word should be from a professional – a police diver who has been involved in recovery operations.

Dorothea, he says, ‘is cold, deep, dark and treacherous. We are baffled by some of the dive practices that go on here.

We have to use ROVs to recover bodies from below 50m, as our absolute operational limit is 50m.' Enough said?

DOROTHEA – DIVERS HAVE THEIR SAY…

While saddened by the recent deaths, I am concerned at the level of hysteria being whipped up in some local newspapers.

I have been diving for three years, am a BSAC Advanced Open Water Instructor, and Dorothea is a regular training venue for me.

Dorothea is 102m deep at its deepest, not throughout. There are areas ranging from 3m through 6, 9, 12, 20, 30, 35 and 40m right up to maximum depth.

There is enough of the quarry at less than 25m to provide a safe and interesting location for most basic scuba training.

It is not beyond the wit of any decent instructor or dive leader to keep less-experienced divers well away from the deeper areas.

Generally divers come well equipped. Many have emergency oxygen and first-aid kits, and have undertaken the relevant training.

In the two incidents I have witnessed, oxygen was available in minutes, mobile phones were used to notify the emergency services and teams of sometimes unrelated divers did all they could to assist.

As diving progresses, recreational divers are able to dive deeper and for longer. Specialist training and high-quality equipment is available, but there is a shortage of training sites of a useful depth.

I would rather see divers train and practise at a site like Dorothea than attempt their first deep dives somewhere offshore.

There is less to cope with at Dorothea, minimal currents and generally predictable visibility.

It is cold, but pre- and post-dive warm food and drink can be provided by using a camping stove. Sea-sickness isn't likely to be a problem, and you won't have to slog 200 miles and hire a boat only to have the weather put paid to the day's training.

If Dorothea is closed, many divers training for deep dives will have to relocate to places like Wastwater in Cumbria.

It's as difficult to reach, and has no first aid or hyperbaric facilities on site, and nowhere near as much relatively shallow, interesting diving.

Many other divers may simply head off to sea with fingers crossed.
Jen Somogyi, Shotton

I have been diving in Dorothea very regularly since the early '90s.

There have been some close calls, such as free-flows and contents-gauge hoses being blow apart, but this has never deterred me from re-entering the quarry the following week, because I have overcome the psychological barriers connected to it.

You can have all the equipment in the world, but if you haven't safely and competently built up to what you are trying to achieve, it's just dead weight that compounds a problem when it occurs.

Psychological preparedness is not saying: ‘I can do this' beforehand, it's built up through gradual experience.

If the hundreds of people arriving at Dorothea each asked themselves a few simple questions without fooling themselves and those around them before entering the water, perhaps more would re-emerge as expected.

Diving in Dorothea is unique and should be viewed as such. People can't just turn up after a lay-off and expect to pick up where they left off, or jump in just to reach a new target depth just because they have come a long way.

Conformity clouds our judgment, sometimes with devastating consequences.

My buddy and I are reminded every week by a plaque to a lost diver that if we make a mistake, Dorothea will be waiting to turn it into something more serious.

So far we have been fortunate. I'm sure others who know Dorothea share my views.
Gary Williams

Next month: Diver correspondent Chris Boardman undertakes a PSA trimix course at Dorothea

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#askmark, Heyo! Longtime listener, first time caller, etc. Went with a BP/W for my first set and I'm having a really hard time keeping the power inflator on my shoulder; the corrugated hose keeps flipping off my shoulder and getting twisted up or just ending up behind the backplate and dangling down the back of the wing. Is there something I can add to my harness to keep it in place? I don't want to tie it to the D ring since I wouldn't be able to lift it to deflate. I'm using the cheap DGX Gears wing for reference. Thanks!

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@jaketarren
#askmark, Heyo! Longtime listener, first time caller, etc. Went with a BP/W for my first set and I'm having a really hard time keeping the power inflator on my shoulder; the corrugated hose keeps flipping off my shoulder and getting twisted up or just ending up behind the backplate and dangling down the back of the wing. Is there something I can add to my harness to keep it in place? I don't want to tie it to the D ring since I wouldn't be able to lift it to deflate. I'm using the cheap DGX Gears wing for reference. Thanks!

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How Do You Keep Your Corrugated BCD Hose in Place? #askmark

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The information in this video is not intended nor implied to be a substitute for professional SCUBA Training. All content, including text, graphics, images, and information, contained in this video is for general information purposes only and does not replace training from a qualified Dive Instructor.
00:00 Introduction
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The information in this video is not intended nor implied to be a substitute for professional SCUBA Training. All content, including text, graphics, images, and information, contained in this video is for general information purposes only and does not replace training from a qualified Dive Instructor.
00:00 Introduction
01:17 Ears
05:13 Scuba.com
06:05 Hydrate
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