One well-known jumping spot is near "our" beach on Gower, South Wales.
Blue Pool is a tidal rock pool about 5 metres across with a sandy bottom, variously measured at 2.5 to 4.5 metres deep (although the locals say it's bottomless).

My grandson, here, is jumping from the left side of the previous photo, about 3 metres. There is a video clip on YouTube of someone jumping from the high rock in the centre of the pic. I hope he wasn't as drunk as the cameraman appears to be!

Phil