Just out to sea, ten meters off the beach, is an under water spring. On a calm day you can see the water turbulance, and pin point the phenomenon. On a baking hot day you can make a B-line for the spring because the spring water is at least 4 or 5 Deg C lower than the surrounding sea water temperature.
Looking further out to sea will show you the Methana volcano peninsula. This geologically active area was, in ancient times, responsible for the lowering of the ground and sinking of the city at Epidauros. Don't worry though, it last errupted in 1700.