An interdisciplinary field of study, underwater life support systems design requires the application of engineering principles with a knowledge of human physiology. Specifically, the study of life support systems design should have a strong background in the following areas: -human physiology related to respiration and the thermo-regulatory system-underwater physics including the interrelationship of pressure and temperature to gas volumes, their properties, and their solution in other materials-the chemistry involved in the absorption of gas constituents including carbon dioxide and other toxic contaminants-decompression theory required to predict the safe exposures to elevated pressure environments-pressure vessel design including design methods for exposures to both external and internal pressures-heat transfer including conduction, convection, and radiation modes-fluid dynamics involved in hydrostatic pressures and pipe flow-psychrometry at elevated pressures required to maintain adequate moisture levels in cabin environments