Nelson is injected with a radioactive material that makes him a walking time bomb.

This episode marks the first appearance of the FS-1!

Cybernetic genius Tabor Ulrich creates a perfect mechanical duplicte of Admiral Nelson. His plot: to make the crew of the Seaview they are fighting World War Three. In doing so, the sub will launch nuclear missles at the China, Russia and the USA. After the holocaust, Ulrich plans to take over and usher in "the age of the cyborg".

Defecting scientists create a proton bomb, but are killed by a foriegn power and the bomb is captured. A surviving scientist works at disarming the bomb...with other plans in mind.

A space probe returns to earth and is recovered by Seaview...only to unleash an alien organism aboard.

A foreign power is salvaging sunken nuke missiles from the ocean floor to make themselves a superpower.

Seaview rescues two men adrift at sea, only to discover they are escaped prisoners intent on not returning to prison. While they attempt to hijack the sub, an undersea creature surfaces to menace the Seaview.

Things go wrong when Nelson and Crane test out a new automated system for Seaview.

With Admiral Nelson away, his old friend Admiral Park takes over Seaview's current mission. Dr. Borgman is conducting experiments, and Park suspects he is up to no good.