Situated in Mt. Ida, the highest mountain on the island of Crete, the Ideon Cave is one of two caves equidistant to the port of Heraklion, laying claim as the birthplace of Zeus. While not as impressive a cave as the other supposed birthplace (Dikteon Cave), any Greek mythology geek will want to visit both sites while vacationing on Crete.
What Ideon lacks underground, it makes up for outside atop Mt. Ida, where views of the entire island are possible on clear days.