The Seaview is being buffeted about by underwater explosions due to the eruption of an active volcano. Dr. Turner (Victor Jory) is aboard to stop the eruptions

The Seaview crew is being entertained by puppet cairactures of the Captain and Admiral, compliments of Professor Multiple. Multiple remains on-board when the sub departs, and his dolls soon come to life, replacing their real-life counterparts. Only Nelson and Crane avoid capture and transformation

"Those who see the Flying Dutchman never, never reach the shore." Investigating the loss of Navy ships, Nelson finds an ancient dagger in a cave on an uncharted island, and falls under a strange curse. Haunted by visions of skeletons and an anachronistic ship, he has trouble convincing the crew of his sanity

Aliens snatch a manned space probe launched from Seaview with Chip Morton aboard, and transport it at the speed of light to their observation post on the rocky, unstable surface of Venus. Checking out the duplicate capsule, Crane suffers the same fate before he even has time to launch. With Chip blinded and a prisoner, and the planet's surface due to undergo catastrophic quakes in a few hours, the odds seem to be against the two men

"There's nothing to do here but to keep from disappearing." Lt. Commander Morton Seaview is carrying a new missile, and Nelson has orders to deliver it to its launch site at all costs

In an attempt to control the planet's tides, Dr. Randolph Mason (a nut if ever there was one -- he is part scientist, part make-up artist!) has invented a powerful electromagnet and established a magnetic field around the moon. The only person who seems to recognize the obvious danger in this silly plan is Harriman Nelson

Doctor Blanchard has created a device to control the actions of a white gorilla. Unfortunately, his assistant Leo Brock wants the fame that the inventor of such a device would gain. As a result he uses the device to enrage the gorilla and kill Blanchard

A man from the future sends two androids back in time to kidnap Nelson from Seaview in order to add him to a collection of other famous military figures abducted from various eras of the past. The plot of this episode is virtually identical to the plot of the ""Time Tunnel"" episode entitled ""The Kidnappers""

Seaview is on the lookout for an enemy sub and its underwater sub-pen. Sonar picks up a contact. The rogue sub fires at Seaview, which is saved only by virtue of her new electronic hull shield

A scientist experimenting with plant life on a remote island has run into trouble. A shore party from Seaview arrives only in time to hear his dying warning that the world will be taken over in eight hours. Nelson brings aboard the only unusual thing he can find -- a red orchid, which proves to be a malign alien (that proceeds to take over his mind and those of the crew)

finds herself suddenly out of touch with the rest of the world, in the wrong part of the ocean and encountering strange creatures. It seems she's been thrown a million years back in time. Then the Admiral opens his cabin door and finds himself back in his Santa Barbara office, confronting the strange Mr

The Seaview is en route to rendezvous with the fleet when Sharkey reports a missle fuel leak. Crane and Morton believe it's worth returing to port to repair, however Nelson knows how to handle it. Taking a small breathing device with him, the Admiral locks himself in the compartment in question to effect repairs

Seaview has been sent to the ocean floor by mysterious pressure impacts. Crane, Sharkey, and Kowalski go out in the Flying Sub to investigate. They, too, are sent to the bottom of the sea

The ghost of Blackbeard is alive and well, and he wants the Seaview and her crew. The pirate 'drafts' Kowalski, who makes a very convincing and quite blood-thirsty buccaneer. Nelson and Crane have their hands full trying to protect the President of the United States (a guest of a Middle Eastern Shah on a nearby yacht), and regain control of their ship

About the plot . .

A lobster-like alien emerges from a capsule retrieved from the ocean floor. He claims that all he wants is one of Seaview's nuclear rods to power his ship for the homeward journey, but neither Captain Crane nor Admiral Nelson is convinced he can be trusted. Victor Lundin also played the neck-braced Hansjurg in Season 2's "The Menfish"

Poor Captain Crane. The things he had to go through. This time, he's in the Flying Sub, when he receives a distress call from the Seaview

"But that's not the goal of a man -- of a scientist!" Admiral Nelson At an experimental station in the Antarctic, the crew discovers a 'tropical paradise' -- but most of the scientists are missing. When two unconscious survivors are brought aboard Seaview, something deadly starts to stalk the corridors. Meanwhile, the temperature outside is still rising

Naval ships have been disappearing, and Seaview is on a hunt for the undersea installation responsible. They find a sea-lab that is not only well-armed but surrounded by overgrown and ferocious sea-creatures. To complicate matters, the guest expert aboard is a traitor

"You had no right -- no right to make that second dive without orders from me!" Nelson to Crane Another scientist with another artificial atmosphere (see Season 1's "The Condemned") that will revolutionize deep-sea diving. When will Admiral Nelson learn! Naturally, Captain Crane is used as a guinea pig for these dangerous experiments. And there are fatal side-effects

Alien jungle growth is spreading across Italy, and before long -- thanks to a crewman who is really an alien spy -- the vegetation invades Seaview too. The Admiral has built a device that might help, but first he and Crane have to fight their way through the overgrown corridors to prevent the missiles being used to spread the infestation even farther. * Patrick Culliton played various crewmen over Voyage's 4 seasons

Seaview is under polar ice, trying to discover the cause of increased flooding around the world. Nelson finds out that Frost Men are in the process of melting the ice cap. The Seaview's reactor is just what they need to finish the job

Aliens are at it again. They're planning to destroy the Earth. However, one of the aliens claims to be a good guy

"Idiots!!!" Admiral Nelson to himself. There is an imposter on Seaview. Lee Crane is the main suspect

". but the Flying Sub's my baby!" Captain Crane to Chief Sharkey Seaview's reactor is running wild -- again. Without taking the time to don protective anti-radiation gear, Captain Crane runs into the Reactor Room to shut down the pile

Seaview experiences a sudden power overload and blows up, killing all hands aboard. When Admiral Nelson (who was at the Nelson Institute at the time of the accident) hears of the destruction of the Seaview, he gets an impossible to refuse offer from Mr. Pem (who survived from A Time To Die): in exchange for the use of the sub's nuclear reactor, Pem will transport Nelson back in time to before the explosion which destroyed Seaview