Submersibles provide a direct means of studying the living ocean resources. Basic submersible types include bathyscaphs, bathyspheres, tethered propelled subs and self-contained subs. Biological scientists require a submersible that is stable, can pinpoint and maintain its position, has variable speed with long endurance and provide excellent viewing and data monitoring systems. Few existing subs meet these needs. Subs can be used to monitor resources not available to other sampling gear, observe relationships of animals to their environment, and determine characteristics of conventional sampling gear. Sophisticated support vessels and diver lockout features will improve the versatility of new generation submersibles.