Treasure Trap is an isometric action game similar to Head Over Heels, but less abstract in its theme. The player guides the diver in a series of rooms (100 total) where the main goal is to collect gold. The main hazard encountered is the sea life that occupied the vacant ship. The character has no weapons, but carries a limited amount of "smart fishes", trained piranhas that attack and destroy all the enemies in the room.

In 1829 The Esmerelda, a cargo ship carrying gold, sinks to the bottom of the ocean. In 1927 a treasure hunter called Howard Kelp dons a diving suit and searches for the bullion in the wreck.