← Dive-sites: Cornwall Quarry


Cornwall quarry (aka Dorothea South) is a roughly 40m deep quarry with very difficult access to the water. It appears as though a climb would be necessary but there is no obvious route down, nor does the path circle the entire quarry – making it hard to find a suitable point of entry.

This quarry was the originally called Dorothea – before the larger pit now known by the same name was opened during mining operations. The pump-house sits to the north, between Cornwall and Dorothea quarry and there may be a tunnel between them (although this is speculation and hasn’t been found).

Since the closure and subsequent reopening of Dorothea quarry for diving (with North Wales Technical Divers), Cornwall quarry has remained closed for diving.


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Key Metrics

RegionPersonnel AccessRoad AccessDepth (m) *Permission neededLat Long (DD)Elevation (m)
Gwynedd (NW)0/5 Extreme1/5 Difficult41No Diving53.053291,-4.244505100

Site Maps

Cornwall Quarry Map

Cornwall Quarry Map


(Click the ‘Lat/Long’ data in the ‘Key Metrics’ section for Google Maps directions)
Currently access is available from the Nantlle Side of the quarry – along the B4418, between Penygroes and Rhyd-Ddu. There is a turn off in Nantlle which takes you west, towards Dorothea. Following the track will lead you to the gate, and after that, the car park.
Can also be accessed from the south by another turnoff from the B4418.
In both cases the track is not maintained and may be closed.

Additional Risks

  • Extremely difficult access


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