Deep and very clear blue water in this disused basalt quarry. A really good swim.
It is private land and access is by trespass only - but don't let that put you off. Access is good and security as far as I am aware is not an issue. Easy to find your way in as there's gaps in the low fence.
People have been scuba diving there. Search for vids on YouTube of people cliff-jumping there.
There is access to the water on the west side, down a steep-ish slope using a rope tied to a tree for help. Alternatively swim from the east side where access is much easier but the surroundings aren't as nice.
The site is a SSSI (Site of Special Scientific Interest) for its geological importance.
Parking on Daisymere Lane Buxton SK17 7JD.