As one of up to four players commanding the Greek ships, you must sail through endless storms, blind to all around you, trying to gather clues to your whereabouts to stay on course. As Poseidon, you throw powerful storms against the sailors, driving them off-course and confounding them, so they can't reach the Sacred Island in time.
The game uses two boards, hidden from each other. The Poseidon player uses special tiles to secretly move one or all the ships on his game board, which shows the real position of the ships, giving information to the sailors about what they see around them. The navigators have to guess where they are, moving their ships on their own game board based on their deductions, as they trace their course to the Sacred Island.
Multiple game boards enhance replayability; special overlays are included to make the game easier or harder, according to the players' preferences.