Sea Dragon is an arcade style side scrolling shooter. The player pilots a submarine through treacherous under water caves in an attempt to destroy a heavily guarded reactor. Mines, gun turrets, and a variety of enemies provide obstacles to this goal. The submarine is armed with missles, torpedoes, and a "Big Kill" weapon (this effects everything on screen) to help the player in the mission. The air supply is limited, so when possible the player must surface to replenish their air supply.