whitelackington said:
If it is flooded by tides, doesn't that make, at least the entrance a SEA CAVE!
For the last time - the river Wye rises due to the tide changes which blocks Otter Hole's resurgence which causes the water flowing through the cave to back up and the sump to close. It is flooded by water which is sinking into the cave whose outflow is restricted by rise in the river level NOT BY THE SEA.
Sea caves are formed in any type of rock due to the action of the sea. What we know as caves are formed in limestone due to the action of carbonic acid (or also sulphuric acid in some places in the world) and also the erosion effect of water flow.
Otter Hole was not formed by the sea and is not near the sea (unless you count the fact that the limestone once was sea bed!). The same thing would happen if you were to build a damn or weir downstream of the resurgence in the River wye - or would you then be asking if it was a Weir Cave or a Dam Cave ???