Probably considered inhumane by today's standards, Seaquest had you machine gunning fish of different size and swimming patterns. You were also charged with taking out smaller enemy subs along the way. One aspect of Seaquest that was interesting for its time was the use of a depleating oxygen bar. After several seconds you needed to bring your sub to the surface to refill your bar, adding to the games difficulty.
Seaquest's most attractive aspect perhaps was its multiplayer mode that allowed you and a friend to tackle the game together while competeing for points. Seaquest will stand for a very long time as one of the early gems of the hobby and a bright spot for the Atari 2600.