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diving in Dorothea, Wales inland dive site

Scuba Diving in Dorothea

Dive Site: Dorothea

Location: Between Nantlle and Talysarn, Gwynedd, North Wales

Description: Inland quarry

Depth: 104.3 metres max (342 feet)

Visibility: 15 metres (50 feet)

Rating: ****

This must be one of the most beautiful quarries there is. The scenery is stunning and the changeable weather creates some amazing colours and effects on the slate and water. This is not officially a dive site, BSAC does not endorse diving here, and there are no on site facilities. The water is very cold, but generally clear. There are many cars and vans in here, a crane from the workings of the quarry, tunnels and garden gnomes. If you are diving deeper, be very careful not to go beyond your limits - many people have died here.

Location map (closest village)

Reader Reviews:

I've been diving at Dotty since I first learned to dive in 1994. There's so much said about how dangerous the place is. Many diving accidents have happened in waters only a few metres deep. It's not the water or the venue that kills people, it's the lack of training or ability on the part of the individual. If divers insist on doing things way beyond their abilities, equipment or training, they'll eventually die.

The site offers something for everyone, in that there are fish in abundance around the upturned truck chassis, ditched cars by the dozen at 35m plus, and the odd tunnel and cave at varying depths. Training ledges are easily reachable at 5, 9 and 22 metres, with all depths in between available for stopping at on the slate heaps.

So Dotty is a fantastic place to dive, in my book, an awe-inspiring site (or sight!), with visibility often in excess of 25 metres. Just dive within your limits of training and experience. BE SAFE!

Ivan Woolley, MSD

I have dived at Dorothea on numerous occasions and although I found the diving fantastic the atmosphere is one of immense eerieness. (Perhaps due to all the accidents that have occurred here!) Knowing this makes you ultra careful to the point of nervousness and paranoia... not for the feint hearted.

Elaine Murphy

I did a try dive before I learnt to dive on the transit van - very clear (and warm at 5m!) water. Despite the stories this is only a dangerous dive site if you don't follow the rules and your own abilities. There are no currents that will sweep you down to the 80m mark - it's your own choice!

Good dives in a pleasant setting.

Peter, Rescue Diver

My first time at Dotty, went down very well. Was dull, cold and raining, but the vis was very good. Saw a few cars, vans and a boat. Went through the tunnel and pony sheds. Would go again in the summer.

John Hayes, Wrexham Seals

I did one of my first dives in this fantastic place and I know that am not qualified to go beyond 35 metres, I still do a 40 - 45 metre dive there as I have done well over 500 dives. I also have the equipment to do these depth plus, as people before have said, you need to know your limits. And if you feel right down there - if not DON'T DO IT is it worth your life to go deep. This is I very good place to do some good diving and if you are good at orientation then you might not have to do much deco, just work up ledge by ledge. What is good is if you go to the gnome garden and then come up the rope to the huts, then round the cliff through the tunnel, then turn left and keep going along the wall you will come to the start again (beware 45 metres max on that dive).

Luke Sharples

Dotty is a fantastic place, beautiful and safe as long as you stay within your TRAINING LIMITS. Sorry Luke you are one of those that clearly admits diving beyond your training and think its ok to do so. Will you be the next Dorothea victim because YOU think you are ok to dive to 45M????


Hi I dive in Dorothea regularly and have done since I first started diving. I have done hundreds of dives there and have extensive knowledge of all of the underwater aspects of the quarry. The maximum depth obtainable is 104.3 metres, that is in a blind tunnel in the bottom sump funnel. otherwise maximum depth varies between 85 to 93 metres with various plateaus /drop offs / scree slopes from there to the surface.

Paul Bell

I visited this place on my holiday and it was amazing, the lake was just breathtaking. I'm going back soon :D


Like all divers everyone likes to push the limit! My personal best being 56 metres off the coast of Libya. Diving can have many challenging aspects but all avoidable if you stay within your training and expertise.

Diving Dorothea requires a more experienced diver,someone who has over a hundred dives of cold water nature. The equipment required should all be cold water approved, from regulators to drysuits and the use of pony cylinders and twinsets. The big must is appropriate dive planning and the question of medical help if any problems do arise. To do a try dive or dive this site as a open water diver, with little experience is in my mind foolish, although have I dived deep, yes but within my training limits and experience. My recommendation, advanced nitrox and extended range by any of the technical diving associations gives the right training for this sort of environment.

Barry Kilnhurst

I don't understand divers who think it acceptable to dive beyond their rated ability. There are courses available to extend your depth range and give you the ability to cope.... is it a money thing for our 'hero' divers? I have done PADI and IANTD courses, I am rated to 48m. Any deeper will require more training.... not a problem.

Keith, Rescue and trimix diver | 26/12/2008

Have dived "Dotty" many times over the last 15 years, a little daunting at first but love it now. I see somthing new on every dive.

64 mtrs, 65mins max, 7°C, viz up to 10m.

Dave, Dive Leader / OWI Instructor | 01/03/2009

For those of you who have admitted to pushing your own personal limits - you must have screws loose. Has your training taught you anything?? If you are fortunate to have families at home, think of them when you play the action hero and for goodness sake - dive within your limits and training.

Map | 09/06/2009

Diving outside of your limits or with equipment not properly serviced/maintained is just asking for trouble. I gave Dorothea the respect it righfully deserved when I first dived it and had a wonderful time. With great vis and fantastic swim throughs in the way of tunnels it makes for a great dive site. It does have a certain eeriness created by the aesthetic location of the site and the 'infamous' reouation. Dive safe and enjoy!!!

John Biggins | 21/02/2010

I dived that in 1997 beyond 25 metres off the ledge and lost buoyancy. Dave Strong took me back up. Make sure your valves regs and cylinders are pre-checked and always listen to your instructor and be careful because it can be very dangerous.

Graham Williams | 06/03/2010

I've been deep enough in Dorothea for the collective fingers to wag at me. There's nothing down there worth seeing. All the good stuff there is no deeper than 27m now since some idiots dismantled the crane at 33ish. Is Dorothea still open? Rumors abound about its demise.

Martin | 17/04/2010

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