This is an old quarry site in the lake district which is easy enough to get to on foot. The cave is really a man made cave with this huge column left in place as extra support for the cave roof (not sure if that's true or not). There is a large opening in one side of the cave walled, called (funnily enough) the window and then two tunnels which lead in and out.
This shot was more luck than anything as we hadn't planned to be here but decided to take a look at just the time when the sun was visible through the window and casting beautiful lighting on the column and water. And this was the result.