North Wales Mine Exploration

Latest update April 30, 2015 Started on August 12, 2014
North Wales has been a hotbed of mining and quarrying activity for thousands of years from the bronze age up to the mid 20th century. This has left many hundreds of copper, lead, zinc, gold, and slate mines for the budding explorer to visit. We are hoping with our ROV we will be able to expand the scope of our explorations to flooded sections of mines and quarries.

August 12, 2014
Expedition's summary cannot exceed 240 characters


Did you know that the National Geographic Society is currently offering Explorers a variety of funding opportunities in the fields of conservation, education, research, storytelling, and technology? To learn more and apply for a grant click here.
If you're not interested in applying for a grant, click continue below
Funded by:

Just another post to appologise for our lack of activity as of late! Doesn't life get in the way!

The cogs have started moving again and we should be back again soon, we have plans a foot for our first few dives and we'll keep you updated on that :D

Looking forward to it! Keep us posted, we're excited to see what you discover!

Any progress on tether modifications? It's a real concern for us, although we don't have slates to worry about. Our primary concern is going from vertical shafts to the horizontal drifts and getting caught up on cribbing or other debris. :(

Just checking in to know we've come out with a neutrally buoyant tether that should be good. Let me know if you're still working on the expedition!

Hi everyone!

I hope everyone had a good holiday.

Sorry for our lack of activity as of late. But we are still alive!

Some modifications planned for the ROV and we shall keep everyone updated on those as we get on with them!

Very cool. thanks for the update. Can't wait to see into the mines. Did you find some of those little fish bobber to pick up your tether a bit? Here's what we use:

Very excited to see the upgrades and next updates!

We're very likely to change the tether completely for an armored (almost) neutrally buoyant one! Watch this space.

I can't wait to see your modification. Being a caver, I'm also looking forward to seeing the mines too!

I'm fascinated by this expedition, and can't wait to see what kind of modifications you add. Curious whether you've solved the tether issue you mentioned in your last post?

Hey! Checking in. What's the latest?

Hey there! We're still alive! Have just fired you guys an email off to your info email address.

Just a quick update, ROV #1511 "Jemima puddle-duck" Survived her first plunge underground!

Plus points - No leaks.
Cons - Tether doesn't seem ideal for mines, kept getting trapped under slates and we were scared of tugging too hard on the tether for fear of snapping the cable. We are now looking at new tethers and the possibility of adding a system to be able to switch out tethers as we see fit.

More pics and videos to follow soon!

Tether management is key. Did you try adding foam fishing bobbers for buoyancy? It's when the tether drags along the bottom that you have problems.

ROV #1511 lives! With only the bare minimum of mess ups I have assembled the beast. It had a quick dunk in a lake and survived, next week should see the first trip underground. Watch this space!


Excellent! Can't wait to see the cave dives!

I love the idea of pushing the boundaries of mines and caves using the ROV!

Nice Build! These cave dives are going to be amazing!
What was the temperature of the lake you test dove? Do you have some desiccant packs taped inside the electronics housing? I'd recommend one or two packs installed and sealed 24 hours pre-dive to pull any moisture out of the air and prevent condensation on the dome in front of the camera.

She has arrived! Assembly will begin toward the end of this week. Hopefully won't be long now until we get her into the water!


Nice, I can't wait to see its first launch!

Well, it's all a waiting game now! Many thanks to the Moore Foundation for the funding and of course OpenROV for sending us an ROV.

Will be keeping everyone updated as to when it arrives and the process of assembly.

In the meantime I have been keeping busy by doing a little wandering around some of our surface quarries.

Dinorwic, the second largest slate quarrying operation in Wales, started around the 1780s and carried on to 1969. Many artifacts of the industrial past remain including the old quarrymans canteen or "caban" still with remains of coats on the pegs and shoes, just waiting for the next shift! In the 70s a hydro power station was constructed deep within the mountain to provide extra peak power. An incredible place to visit and well worth a look if you happen to end up in this part of Wales, the old workshops have been preserved as a free museum to the slate heritage of Wales.


As well as flooded underground workings there are many flooded quarries, Amongst one of the biggest and deepest is Dorothea at its deepest over 100 meters. A notorious place for divers having become known as "The incident pit" due to the many divers who have lost their lives here, despite this it is still a very popular place for divers. Dorothea opened in the 1820's and quarrying continued up until 1970 when the pumps were turned off and water began to fill the quarry leaving many buildings and various pieces of equipment in place. We hope to be able to see some of the lesser seen parts further down.

There are also various other pits around Dorothea that are flooded and could hold potential interesting quarrying artifacts.


Whoa cool! I'd love to see what kind of big quarry equipment is flooded down there!

Hope you guys get your Explorer Agreement soon! I wanna see the bottom of that quarry - without having an 'incident', haha.

@Blober any updates on your paperwork to get access? I'm curious about the permitting process you go through, it's something we all face at some point. Any info is good info!

@erikabergman We don't really require any paperwork to access many of the sites. We may require permission for one or two places but the majority are open. We're quite lucky here! The first mine the ROV will be tested in has a locked gate with a combination lock which you need only ring up and ask for the code.

Artifacts are not always industrial in nature. If you look underneath a slate in a nice dry corner you might just find some remains from the miners. I always wonder about who hid these under a slate 80+ years ago, was he just having a small moment to himself and trying to forget he's hundreds of feet underground? Was he with his mate having a rest from a hard days quarrying? Was he just sneaking a quick break from the management? Did he end up fighting in the war? Did he survive that? I'll never know, but its nice to imagine, guess I'm an old romantic for this kind of thing.


Very cool! And totally agree. Some of our favorite parts of exploring the Hall City Cave were the stories of other cavers who'd gone looking for the treasure.

Not far from the connection between Cwmorthin and Oakeley slate quarries lies chamber 34 incline winder. Built in 1934 originally used as a dual winder but reduced to a single, was powered by an electric motor. The speed was controlled by using a brine bath and the voltage/speed altered depending how deep the elements were immersed. Oakeley was at one point the largest underground working in the world with an estimated 50 miles of underground track. Underground operations ceased in the 70s and open casting continued until 2010.

We are hoping we can find similar things in flooded sections of mines.


Holy Moly this is cool! Is there anything chemically dangerous in the water, or is it just crystal clear ground water?

The water in the slate quarries is usually very clean, the mineral mines tend to have more nastiness in them, but its fine as long as you are not drinking it!

Oakeley chamber 34 incline, connected together floors DE to I and was driven around 1934. Floor H was once de-watered when the neighboring quarry was pumping out the opencast pit but nothing is known of what lies beyond on floor I. With an open ROV we could discover what lies beyond!


Another example of a North Wales slate mine with flooded lower workings. The pumps were finally switched off here in 1999 allowing water to rise slowly over the next decade or so. It now appears to have reached a stable level as gauged against the steps of a "manway".
The floors here are around 70ft apart with at least 2 levels below water.
Although this mine was worked as late as the 1990s, earlier sections had long been abandoned, often with ancient artifacts left in place. These may take the form of miners' personal effects such as clay pipes, lamps and tools or mining infrastructure like rail lines, trucks and bridges.

An openROV would allow us to get beyond the tantalising glimpses we're currently afforded of this lost world.
But time is of the essence. Modern day untopping work is threatening access to this particular mine with some unique sections already lost.


In North East Wales, a substantial, underground lake was discovered by miners in 1931. Flooded to hundreds of feet below sea-level, its true depth has long been the subject of speculation. Several thousand gallons of water a minute run through, draining to sea along miles of man-made tunnel.
This crystal clear water provides excellent visibility but diving is precluded by the long and arduous access route.
Exploration by ROV appears the obvious solution and would provide an invaluable insight into this fascinating natural cave system.


That photo is incredible! I'm really excited to follow along with this expedition!

Expedition Background

Many of the mines in North Wales have flooded levels, inclines, shafts and stopes. An open ROV would open up our world to what we would be able to see. We have caught glimpses of equipment in flooded sections using high powered torches but these can only cut through so much and leaves us wishing to see if more lays further beyond.

I will be uploading various photos of mines over the coming weeks and updating everyone on what we have been getting up to, a group of us usually meets up every Thursday night for an evening of mine exploring so expect updates from us at various points!

The photo included in this post is taken in Cwmorthin slate quarry. Slate extraction started in 1810, underground quarrying started around 1861 and continued to 1970, where much smaller scale quarrying took place until the 90s when the quarry finally shut. It remains a fantastic example of Victorian industrialism


Whoa! Stunning photo. Can't wait to see more!

Contribute to this expedition

Email Address
Number card
Postal Code

Review Your Contribution

You have chosen to contribute to expedition.

Confirm your details:

  • Name:

  • Email:

  • Last 4 digits:

Click below to proceed.

Thank You for Your Contribution!

Fundraising Details:


Tell us how raising these funds will impact your expedition
You're almost there, we just need to know three more things:
Is any part or component of your project funded by the National Geographic Society or a National Geographic Society Grant?
Is anyone on your expedition/project team affiliated, either currently or in the past, with the National Geographic Society?
Did you apply for a grant/funding from the National Geographic Society for this project?
You have a goal to raise by for:
Is any part or component of your project funded by the National Geographic Society or a National Geographic Society Grant?
You’ve responded:
Is anyone on your expedition/project team affiliated, either currently or in the past, with the National Geographic Society?
You’ve responded:
Did you apply for a grant/funding from the National Geographic Society for this project?
You’ve responded:

Thank You

Fundraising is almost live!
Thank you for applying to collect contributions! We will review your request and follow up with next steps via email.
Feel free to email us if you have any questions.