Voyage to the Bottom of the Sea (1964)

S1E5 The Price of Doom

Title: The Cost of Catastrophe Plot: An Antarctic research duo, a husband and wife team, meets a tragic fate as their experiment with plankton spirals out of control. The Seaview is dispatched to examine the situation and collect plankton samples. However, the submarine soon finds itself threatened by the grotesque, invasive biomass. As Admiral Nelson, Captain Crane, and the crew grapple with this new peril, they must also contend with a hidden danger: one of the three scientists aboard is secretly an enemy operative.