In Search of Dr. Riptide

You are Nick Nautilus, Secret Naval AgenT (S.N.A.T.) 1138.

S.N.A.T. 1138 Mission Summary:

You have been called into action to seek and destroy the undersea
laboratory of Dr. Tiberius Riptide, a mad scientific outcast. You
have been ordered to use any means necessary to put Dr. Riptide and
his secret lab out of commission...for good.
A JASON submersible will be issued to aid your search. The JASON's
small, manageable size will make it an invaluable asset.

Mission Background:

Riptide was banished from the scientific community after he
announced plans to construct devices of heinous mass
destruction to the population of the world's oceans.
Intelligence has reported that Riptide has finally developed his
Tuna-Matic, a device that turns living matter into a marketable
delicacy. Riptide is fast becoming a rich villain by selling his
"Tuna" on the black market as a trendy food for the filthy rich and
powerful. Riptide has hidden himself deep within underwater
catacombs off the coast of Australia and has surrounded himself
with deadly protection. You will come face to face with many of
Dr. Riptide's creations and traps, so be prepared. If you reach
his lab, Riptide will be waiting for you, and he will have no regrets
shipping you out in a tuna can!

A side-scrolling DOS game set in the Great Barrier Reef.