Meet Lake Vouliagmeni,one of Greece's strangest and most underrated natural wonders, just 20 minutes from Athens. It's a thermal lake that formed when part of a limestone cave collapsed thousands of years ago, so the water stays a constant 22–29°C all year round, fed by an underground spring system connected to the sea. Locals have been coming here for centuries for the mineral-rich waters, believed to help with arthritis, skin conditions and rheumatism. But the real party trick? The doctor fish

Acropolis Athens: Sunlit Views of Athens Greece