Last week I had two spectacular dives into the Caves of Grotta Giusti Natural Spa.
The caves run along a fault line in the mountains that reaches 900 meters deep and extends 10 km along the mountains.
It was a fantastic experience and can only recommend this to other fellow scuba divers. It is narrow, dark, special equipment but with 200 meters of visibility and no current and lovely warm (However, don’t do this as your first after certification)
If in Tuscany, Italy go a visit and jump into the 34 deg C warm water and see for yourself.
Until then, you can check out this video.