In Shark! Shark!, the player takes the role of a small fish in a body of water. The goal is to eat fish that are smaller than yours, and avoid being eaten by fish larger than yours. Periodically a shark appears on screen and attempts to eat the player. A shark can be defeated by biting its tail. Lobsters and crabs also appear at the bottom of the screen and jump up to try and grab the player. The game has no end, the goal is just to get the highest score by eating fish and killing sharks, lobsters, and crabs.