S84-36956 (1 July 1984) --- Astronaut Robert L. Crippen, 41-G crew commander, prepares his SCUBA mask prior to submerging into the weightless environment training facility's 25 ft. deep pool to observe a simulation exercise for two fellow 41-G crewmembers assigned to an extravehicular activity (EVA) in space. Not pictured are Astronauts Kathryn D. Sullivan and David C. Leestma, mission specialists who will perform the EVA during the eight-day mission scheduled for October of this year.