Just around the edge of the lake from central Ioannina, this cave is among Greece’s largest and most impressive. Discovered by accident in 1940 by residents fleeing bomb attacks, 1100m of its fairy-tale passageways can be explored on hourly guided tours (45 minutes, in Greek and English). Knowledgeable guides come armed with fascinating facts about geology and unique cave fauna. The cave is usually colder than outside, so dress accordingly.
Buses 8 and 16 from Ioannina’s clock tower run regularly to Perama, 250m south of the cave.