Mr. Pem plans to use his time device to alter the course of history.
A reactor explosion creates a bizarre fourth dimension of time and space.
While en route to deliver a secret defense device, Nelson is warned there is an enemy agent aboard.
Nelson, Crane and a peace-loving alien avert intergalactic war.
The Seaview travels to the polar icecap to find the reason for world-wide floods.
The crew battles an alien plot to overrun Earth with jungle growth.
Crane is turned into a beast-like creature as the result of experimental descents in the diving bell.
The crew searches for a hidden sea lab where highly sophisticated weapons are being used against the Allied Command.
The crew of the Seaview travels to Antarctica to investigate the fate of a scientific expedition.
Capt. Crane returns to the Seaview to find Nelson and the crew involved in a plot to destroy Washington, D.C.
The Seaview takes aboard a UFO containing a lobsterlike alien.
The crew matches wits with a malevolent leprechaun who's searching for buried gold.
Blackbeard the pirate plans to take over the Seaview and use it to continue his pillaging ways.
The leader of an amphibian race plans to capture the Seaview and harness its nuclear power.
After using an untested emergency breathing apparatus, Nelson's increasingly paranoid actions put the entire crew in danger.
After experiencing a strange jolt, the Seaview surfaces to encounter prehistoric creatures.
A dying botanist tells Nelson that aliens will attack mankind in eight hours.
The Seaview plays a deadly game of cat-and-mouse with a mystery sub.
A man from the future plans to add Nelson to his group of zombie-like military officers.
Nelson nearly loses his life when he becomes interested in a friend's scientific experiments on animals.
A scientist uses an electromagnetic field to draw the moon closer to Earth.
Hallucinations plague the Seaview men who are on a mission to deliver secret missile.
Nelson, Crane and Morton are transported to an alien planet.
The Seaview encounters the ghostly Flying Dutchman.
A puppet master replaces the crew, one by one, with look-a-like puppets.
An elderly alchemist jeopardizes the future of the Southern Hemisphere when he tries to obtain a substance that prolongs life.
Nelson is brainwashed into attempting to destroy the Seaview.
The Seaview crew investigates after a mysterious cloud causes widespread destruction around the world.
A crew of wax dummies takes over the Seaview.
Extragalactic creatures hope to use the sub's power to populate Earth with their own kind.
A huge, amorphous sea creature threatens the Seaview, crippled and short of air on the ocean floor.
An energy mass from a foreign galaxy takes control of the Seaview.
The Seaview transports a mummy, which awakes and attacks Crane.
A mermaid leads the sub to an undersea nuclear bomb that's about to explode.
The Seaview faces a new threat, fossil men who plan to take over the world.
The Seaview battles an alien heat monster at a remote Arctic space listening station.
Crane and Kowalski discover Nazi officers in suspended animation.
Crane is attacked by an amoeba-like creature that sends out bolts of electricity.
Adm. Nelson goes on a rampage after exposure to radiation causes a return of the werewolf virus.
The Seaview battles an enemy sub for control of an activated superbomb.
The Seaview crew faces a battle with plant monsters created by a scientist who is telepathically controlled by his brother.
The Seaview is fired upon by a 200-year-old, square-rigged frigate.
Aliens attempt to take over an underwater atomic base.
Subliminal messages tell Crane and Nelson to kill each other.
The Seaview searches for a monster that caused the deaths of a film crew.
The Seaview rescues Kowalski's brother who in turn saves the sub.
An alien causes the Seaview nuclear pile to build dangerously.
Aliens use six windup toys in their bid to gain control of the Seaview.
Nelson is shipwrecked on an island and attacked by a monster.
A senator hypnotizes the crew, and they lose contact with the world.
A wolf attack turns a scientist into a werewolf which then claws Nelson.
A creature that is pure brain tries to take over the Seaview and use it for its body.
An apparition takes over Crane's body after forcing Nelson to shoot him.
An android discovers an unknown element that produces unlimited energy.
A disturbed scientist, obsessed with creating a manfish, is granted the Seaview facilities to complete his experiments.
The crew is terrorized by a giant spider while trying to retrieve explosive fuel cylinders from a wrecked nuclear sub.
A saboteur damages the Seaview to prevent a peace conference.
The Seaview encounters a 16th-century pirate and his ship.
Crane and Nelson try to keep a giant whale that has swallowed an atomic bomb away from the president's ship.
A scientist will do anything to retrieve his research data from a sunken ship that is being guarded by a giant Portuguese man-of-war.
A U.N. official sabotages attempts to put out a fire in the atmosphere.
The ghost of a German U-boat captain tries to convince Nelson to murder Crane so the German can take over his body.
The crew of the Seaview have their hands full as they come up against two escaped convicts and a sea monster at the same time.
An enemy sub captures Crane and steals missiles from the United States.
The Seaview lands on a volcanic island inhabited by dinosaurs.
The Seaview recovers a space probe with a strange growth attached to it.
Several unmanned automatic drone defense subs inexplicably fire their missiles toward the United States.
Enemy agents kidnap a scientist who developed a deterrent weapon.
The Seaview searches for a force field which destroyed three space capsules.
Crane pursues a scientist who threatens to destroy the world.
A scientist discovers a fissure which reaches to the earth's core.
Crane and the president of the United States are trapped inside a bomb shelter.
Adm. Nelson struggles to stop a subversive plot to infiltrate the Defense Department.
Police and enemy agents hunt Crane through the streets of Venice.
A scientist kidnaps Nelson and creates a cyborg containing his knowledge.
The Seaview attempts a rescue of the survivors of a sunken submarine that has been trapped in a cave for 28 years.
Adm. Nelson is turned into a human time bomb in a plot to start a war between Russia and the United States.
While attempting to salvage the remains of an underwater laboratory, Nelson and a Russian scientist are swallowed by a whale.
Adm. Nelson's sister is kidnapped by enemy agents, forcing him to reveal the location of underwater missile silos.
An egotistic scientist conducts experiments aboard the Seaview.
The Seaview investigates reports of a murderous monster in Scotland's Loch Ness.
Foreign scientists try to turn Nelson and Crane into enemies.
Nelson is stranded on a life raft with leaders of a hostile power.
Scientists conduct experiments changing humans into amphibians.
An experiment with accelerating the process of evolution threatens the lives of everyone on the Seaview.
Crane is brainwashed and ordered to thwart a mission and kill Nelson.
Crane should be the only person aboard the Seaview on an automated mission, but he is not alone.
An insane art collector uses the Seaview in an attempt to steal the Mona Lisa.
Scientists discover a robot has been reprogrammed to cause destruction.
A capsule containing a creature that has been preserved for millions of years is taken aboard the Seaview.
The United States mistakes a satellite launch for a nuclear attack.
Nelson appears to have a breakdown after a huge jellyfish attacks a submarine.
Adm. Nelson is captured by a cult of neo-Nazis intent on destroying the U.S. and Russia.
An injured U.S. president comes aboard the Seaview for treatment.
The Seaview rushes a young prince back to assume his country's throne before a new faction can take over.
A scientist enlists the Seaview's help in locating the huge whale that crippled him.
A scientist tries to discover the cause of blizzards in Florida.
The men of the Seaview become involved in a maze of spies while attempting to smuggle a defecting agent to the U.S.
An entertainer offers information about a weapon that threatens world peace.
An explosion in a minefield damages the Seaview, and it sinks.
The Seaview carries two Russians to disarm a satellite about to fall on San Francisco.
The Seaview investigates reports of a monster in the North Sea.
While investigating bizarre occurences in Antarctica, Nelson and Crane become trapped in a prehistoric world.
The Seaview loses its power system while investigating a spacecraft that fell into the ocean.
Plankton samples expand, breaking the bulkheads and threatening the crew.
The Seaview goes to the rescue of a Latin American president and finds his ship abandoned.
An enemy agent introduces a fear gas into the ventilating system.
Crane investigates the mysterious disappearances of two research ships.
The Seaview is sent to avert global disaster by detonating a nuclear device under the polar ice cap to counteract the potential seismic tidal waves generated by a predicted polar earthquake.