Two of the railway tunnel cuttings in the "pyramids"
Eryri (Snowdonia) North Wales Walks & Hikes Welsh Slate

Dorothea Quarry Walk

Header image including six images from the Dorothea Quarry Walk

During Gwynedd Business Week I had the pleasure to attend a Llechi Cymru event to hear all about the Welsh Slate World Heritage Bid. It was a great event held at Pant Du vineyard which is a great place – somewhere else I need to visit in Snowdonia this Summer (the list just keep growing). As part of the event there were two tours available – a tour of Pant Du vineyard with the owner Richard Huws or a walking tour around Dorothea Quarry with Dr David Gwyn. I wasn’t sure which one to go with so my lovely Instagram followers voted for the quarry tour which I’m glad about because after thinking about it, it isn’t often you get to tour an old quarry with the leading expert on Welsh slate is it?

Dorothea Quarry

If you’re a diver or live locally, it is likely that you will know about Dorothea Quarry. The lake is a very popular spot for divers and notoriously dangerous as it is said to be the deepest lake in Snowdonia. Apparently it is so deep that no-one has reached the bottom and numerous people have been injured there. I understand that so far I’m not really selling the place to you but basically, don’t go diving (or tombstoning) and you’ll be fine.

A Brief History

I digress. Dorothea Quarry was one of the main quarries in the area by the late 1800s and produced approx 17,000 tons of slate at it’s peak. By the 1930s there were 350 men working at Dorothea. However due to the Second World War production dropped and the quarry never fully recovered. The quarry was closed in 1970. Once the quarry was closed the pumps were switched off and thus the quarry flooded leaving the beautiful lake we see today.

Relics amongst the trees at Dorothea Quarry

At the entrance to the site, Dr David Gwyn took us in to the trees to show us some old relics. He explained that it used to be a dwelling and outbuildings which were actually inhabited until the 1970s. I find it amazing that the buildings fell into such disrepair in short space of time. As Dr David Gwyn said, this place would be amazing if it was redone and turned into artisan units.

Train Sheds and Railways

A view of the old railway line cutting at Dorothea Quarry

Further along the walk he took is back into the trees to show us an example of an old farmhouse. He said that in many books one of the buildings is described as an old barn which he says isn’t accurate. The old barn they refer to was in fact an old train shed where up to 6 trains were kept. These horse drawn trains were used to transport slate from the valley to the docks at Caernarfon. What was fascinating is that unlike the Ffestiniog Railway (used to transport slate from Blaenau Ffestiniog to Porthmadog) which was a downhill gradient, the railway at Dorothea and Dyffryn Nantlle was a very “up and down” route meaning that it was extra work for the poor horses.

Pyramid Tunnels

Two of the railway tunnel cuttings in the "pyramids"

From the barn he took us around the lake and through the “pyramid tunnels”. The tunnels were just archways in the massive man mad inclines. Unfortunately these incilnes are now starting to fall apart and a lot of that area has been fenced off for safety reasons. It was fascinating to see the how much of the structures had cracked under the pressure.

Cornish Mill

Cornish Mill House

On the homestretch we stopped by the old Cornish mill. It is a marvellous structure built in 1904 and it housed the Cornish Beam Engine. You cannot go into the building as it’s been closed off again for safety. Not that it stops idiots but I guess Darwin’s theory of evolution might stop them eventually. There is a video on YouTube which shows a group of young adults climbing over the pit and laughing because they almost fell in. It’s stupid and reckless so I won’t share it here.

As Dr David Gwyn said, it’s a shame that it can’t be restored as it would cost a fortune to do so. I may or may not have committed to funding it’s restoration if I win the lottery.

The Lake

The lake at Dorothea Quarry

It’s a shame we only had an hour for the tour as I could listen to Dr David Gwyn all day. His knowledge about Welsh slate history can’t be beaten. There is so much he could’ve shown us there but alas I’ll just have to go exploring on my own. The view of the lake is just spectacular and there are plenty of places to sit down and have a picnic. Highly recommend this walk and I know I’ll be back soon to investigate properly.

Have you ever been to Dorothea Quarry?

Dorothea Quarry is an abandoned slate mine in the Nantlle Valley, Snowdonia, North Wales. It's an amazing place for a walk with history at every corner.

One Comment

  1. Wow, the pictures are amazing! I would love to visit the quarry, it looks so impressive.

Leave a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.