While on a routine scientific expedition Capt Crane encounters a strange hybrid seaweed humanoid creature. Crane is captured by the creature and the crew of Seaview launch a desperate attempt to rescue Crane before his air runs out.
The Seaview encounters a strange structure on the sea floor. Investigating they discover a German submarine from WW2. Surviving Germans on-board think the war is still being fought. And they have weapons on-board of unimaginable destructive power.
While on routine patrol the Seaview begins to hear strange noises coming from an undersea canyon. Investigating they discover the source of the noise and the power behind the destruction of a British fleet in the area 200 years before.
The Seaview is tasked with transporting a Mummy from New York for special secret testing. It becomes apparent very quickly not all is as it should seem, and soon a terrible threat is unleashed on the crew of Seaview.
The Seaview is tasked with attempting a space probe launch from sea. To avoid interference a skeleton crew is manning the ship. While en route the ship encounters a strange object that unleashes a threat that could destroy Seaview and all on board
The Seaview is tasked with moving a series of crates supposed to contain statues dating from the time of Atlantis. Something far more sinister is in the crates and Capt Crane is the only one in a position to save the ship.
Crane and the Admiral are on a mission to secure a new element that could be used to control the world. While exploring an undersea cave events occur that leave the admiral as the only survivor of the expedition and a changed man.
The Seaview is sent to stop an active volcano from erupting and causing a catastrophe. Accompanying them is Dr. Turner who's suppose to help them. But it turns out he has a different plan and that is to make the volcano erupt so he can acquire something that will make him immortal.
A puppeteer comes on board to entertain the crew. But it is later revealed that his puppets are alive and they plan to take over the sub. That's when they replace the crew members with duplicates. Only Nelson and Crane are left to try and stop them.
When four capital ships vanish, Admiral Nelson and Commander Van Wyck are sent to investigate. They find an island where Nelson removes a dagger from a skeleton which happens to be the captain of the Amsterdammer, the Flying Dutchman, and is then cursed. Van Wyck is in reality the first mate who killed the Captain. His plan is to kill Nelson with the dagger so that he can be free and Nelson will take his place.
Aliens from the planet Centaur bring a capsule containing Commander Morton to Venus. They want to keep earth from invading their planet and kidnap Captain Crane in an attempt to bring the Seaview to their planet.
When a top secret Neutron Bomb begins leaking radiation, Seaview crew men begin disappearing and those who haven't begin seeing things. The Seaview is racing the clock to fire or disarm the missile before it explodes.
Admiral Nelson and Captain Crane are shocked to see a scientist shot to death during a live televised news conference viewed from the Nelson Institute. Especially shocking is that the killer appears to be Admiral Nelson. Both Nelson and Crane are eventually able to overcome efforts to stop them from boarding the Seaview. The submarine races to stop an earth-threatening project set in motion by the radical scientist, who may not really be dead after all. In the meantime, a very dangerous master of disguise causes mayhem and confusion as he tries to stop the Seaview ...
A scientist friend of Nelson has developed a device to control a rare white ape. The scientist's jealous assistant causes the beast to kill the scientist and the ape runs wild after being brought aboard Seaview causing destruction.
A man named Alpha from 2823 sends 2 Collectors to bring Nelson to his time to add the Admiral to his collection of military officers. Chief Sharkey goes to the future to help while the Collectors wreak havoc on the Seaview.
The original Blackbeard takes over some of the Seaview crew including Kowalski to blow up a ship carrying King Solomon's Golden Throne. The remaining crew try to find a way to disable Blackbeard's power source.