The basic design and selection of oil rig equipment offshore is greatly influenced by the ability to maintain and service such equipment as and when required. A critical analysis of underwater work systems was made and primary research and development conducted that has resulted in advanced new diver alternative systems. Two new systems, a one person one atmosphere microsubmersible, DEEP ROVER, and a robotic device, RIG ROVER, both equipped with newly developed sensory manipulator systems are described. These systems markedly improve work capability subsea and may influence future offshore developments, particularly in deep water.