Mike tries to free the pilot of a downed jet from his watertight cockpit before his air runs out, without causing the man’s death from the water pressure.

Nelson and Crane hear about the destruction of the submarine Angler. When they read the captain’s log and hear the tapes made in the control room, Nelson and Crane are…

The cre of the Seaview is called to investigate an undersea laboratory where scientists are surgically transforming humans into amphibians.

Crane is brainwashed by enemy agents, and his new mission is to deactivate certain strategic undersea missiles and to assassinate Admiral Nelson!

After returning from a mission on deep space, a lifelike robot is brought aboard the Seaview, but the crew soon discovers that the robot has been mysteriously reprogrammed to wreak…

Admiral Nelson is kidnapped from a plane during mid-flight and held on a remote island by Nazis who plan to conquer the world.

Nelson and Crane go undercover and risk their lives in order to bring a Communist defector back to the United States. But the man is injured in the attempt, and…