The game board shows an ocean in which the animals are just shown as shadows. Under the board, face-down tiles are placed in a random order.
On a player's turn, they reveal a tile and can place it on the board (if the space under it is already occupied) or put it face-down above the board (trying to remember where it is). A player can always choose to reveal a tile from above or below the board.
When a player manages to complete the picture of a sea creature, they move forward on the score track.
When the ocean has been completely revealed, the player with the highest score is the winner.