The war is over, and the Greek ships are trying to return to their homeland after a long absence. They need to reach the Sacred Island to present offerings and prayers to the gods, but the irascible Poseidon will use all his power to prevent them from getting there.

In Odyssey: Wrath of Poseidon, one player takes the role of Poseidon, God of the Sea, while the others become navigators in search of the Sacred Island. Gameplay takes place on two copies of the same game board that are separated by the game box so that they are not visible to one another. The Poseidon player throws powerful storms against the Navigators, driving them off-course and confounding them so that they cannot reach the Sacred Island in time. Only Poseidon knows the real position of the ships as indicated on his copy of the game board.

The navigators must sail through endless storms, blind to all around them, trying to gather clues to their whereabouts to stay on course. They also track the position of their ships on the game board, but the positions indicated are only a best guess — and they can become increasingly inaccurate as the game progresses.

The navigators must use their wits to stay on course and reach the Sacred Island before the end of the game, while Poseidon wins by preventing them from reaching their destination.