An ace out at sea?

• A skilled worker who can live in underwater installations and participate in scientific research
• Bathysphere user
• Undersea explorer
• Sealab dweller
• Cousteau, perhaps, has an alternative for us
• Sub tenant?
• Cousteau, for instance
• Skilled underwater worker or scientist — an ace out (anag)

Wiktionary Word definitions in Wiktionary
n. 1 An explorer in a submarine. 2 Someone who lives or works underwater, for scientific reasons.