'Raptures of the Deep' by Alan Fennell

When the Stingray crew goes to the rescue of two crazy treasure hunters, Troy inadvertently falls down a crevasse. He quickly runs out of air and slips into unconsciousness… and then dreams that he is the richest man in the world, living in a fabulous undersea castle with Atlanta and a talking Marina. But then the Aquaphibians attack…

Don Mason (Captain Troy Tempest), Robert Easton (Lieutenant George Lee ‘Phones’ Sheridan / Agent X20), Lois Maxwell (Lieutenant Atlanta Shore), Ray Barrett (Commander Sam Shore / Lieutenant Fisher / Titan), Sylvia Anderson (Marina)

Directed by Desmond Saunders
Produced by Gerry Anderson

TX (UK): 29th November 1964

Notes:
*Featuring Captain Troy Tempest, Lieutenant George Lee 'Phones' Sheridan, Commander Sam Shore, Lieutenant Atlanta Shore, Lieutenant Fisher and Marina