There's a spectacular trio of caves on the Mani Peninsula’s west coast, just 37 kilometers (23 miles) from Gíthion. The caves were inhabited by people from Paleolithic times, but that ended when an earthquake struck the region in 4 B.C.E. Today, locals conduct boat trips on an underground lake here, taking visitors down narrow channels and into illuminated caverns festooned with stalagmites and stalactites. The boat tours take about half an hour, and the guides generally give their commentary in Greek only, but ask if your guide speaks English—many do. Note that you'll need to negotiate some steps to reach the entrance to the caves.