The grotto itself, which is about 150 ft.
The grotto, situated in the southern face of the isle, is 2 27 ft.
There are also hot springs and a sacred grotto of Apollo.
The Franz-JosephElisabeth grotto, the largest of the four, and the farthest from the entrance, is 665 ft.
Half way up the cliff, but some distance south of the citadel, is the grotto of Montfat, alleged to be the site of Diana's shrine.