← Dive-sites: Cwmorthin Mine


Cwmorthin is an extensive and large mine next to Blaenau Ffestiniog. It’s main entrance is not far from the shore of Llyn Cwmorthin, a lake formed near the spill of the mine.

The mine itself is used by many of the adventure companies in the local area and the keys are available for free to experienced people. Much of the deeper sections are flooded but some of those that aren’t are equipped with pitches, zip-lines and traverses.

I’ve no idea if any of the mine has been dived but it appears there are certainly sections which would be suitable to those who are trained to do so.

Much more information is available at The Friends of Cwmorthin Slate Quarry and AditNow Mine Exploration & Mining History website.


Entrance to Cwmorthin Mine

Entrance to Cwmorthin Mine

Key Metrics

RegionPersonnel AccessRoad AccessDepth (m) *Permission neededLat Long (DD)Elevation (m)
Gwynedd (C)-/5 Unknown-/5 UnknownBy Appointment52.997641,-3.969211323

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