Stingray (1964)

S1E19 Deep Heat

While searching for a missing robotic probe, Stingray finds itself at the depths of a volcano where two survivors from a ravaged city plot to commandeer the vessel in a bid to escape the looming eruption. However, when Marina secures the hatch, they must go back to save Troy and Phones, who are stranded and in peril. With only two sets of breathing equipment available, Troy and Phones must depend on their WASP training to navigate the treacherous waters back to Stingray.