1) Aquanaut 2) Bathysphere user 3) Sealab dweller 4) SEALAB inhabitant 5) Skilled worker 6) Skin-diver 7) Trained worker 8) Underwater explorer 
oceanaut 1. An underwater swimmer in an ocean who uses an underwater breathing device. 2. A skilled worker who can live in underwater installations and participate in scientific research.
noun a skilled worker who can live in underwater installations and participate in scientific research