The Undersea Environment (1983)

From the back:

The Undersea Environment is a Traveller supplement dealing with the particular problems found in an aquatic environment. Included are specific rules systems designed to simulate underwater activities and hazards, explanations of gear and equipment available for underwater use, and a guide to special events and encounters to aid the referee in constructing underwater encounter tables.

Challenge your players to broaden their horizons and enter The Undersea Environment.

This sourcebook is paired with The Drenslaar Quest, a full-length adventure making use of material presented in The Undersea Environment.