Defo not Elm Hole. Cathedral Cave? This is a guess, on the basis that I've never been to the cathedral cave resurgence and just don't recognise the resurgence in the picture... There's a dive line coming out and the sand is similar to that found in places in DyO.
The first two pictures I was going to post I rejected as too obscure, neither being on the Cave Registry yet - this was intended to be a more obvious challenge. I thought the woods visible beyond the cave entrance would be a clue.
I will settle for identification of either the cave picture or the resurgence cave entrance. They are both on the Cave Registry and both south of Ogof Draenen.