The word ‘breathtaking’ is bandied about so much it seems to have lost its impact. But Melissani Lake is deserving of the adjective. Discovered in 1951, it’s 22 metres below ground and 30 metres deep. A century earlier, an earthquake shook the cave and collapsed the roof, leaving a massive hole in the ceiling. Hop on a boat and let a guide steer you through the electric-blue waters.