The controlled explosion of an atomic bomb in the Arctic Circle awakens a frozen dinosaur that will wreak havoc in New York City.
When scientists exploring the Amazon River stumble on a “missing link” connecting humans and fish, they plan to capture it for later study. But the Creature has plans of his own, and has set his sights on the lead scientist's beautiful fiancée, Kay.
Julie, an American on vacation in Mexico, spots a giant, one-eyed amoeba rising from the ocean, but when she tries to tell the authorities, no one believes her. She finally teams up with a marine biologist in an attempt to destroy it.
In a tributary of the Amazon, a monster – half-man, half-fish – is captured and placed in a reservoir in a Florida national park to be observed by scientists.
A marine biologist and a government agent investigate mysterious deaths and rumors of a sea monster in a secluded ocean cove, and find themselves involved with a marine biology professor conducting secretive experiments, international spies trying to steal his secrets, a radioactive light on the sea bottom, and the malevolent thing which guards it.
Scientists surgically transform the Creature into an air-breather, but being able to live on land is not enough to make him comfortable with humans. Enraged, he turns his wrath on anyone who comes near as he desperately tries to return to the deep-water world where he truly belongs.
A mysterious hypnotist reverts his beautiful assistant back into the form of a prehistoric sea monster that she was in a past life.
Giants Mollusks are released from the earth by an earthquake and start killing people.
Navy Commander Alan Roberts is assigned to lead an expedition to Little America in Antarctica to investigate reports of a mysterious warm water inland lake discovered a decade earlier. His helicopter and its small party, including reporter Maggie Hathaway, is forced down into a volcanic crater by a fierce storm. They find themselves trapped in a lush tropical environment that has survived from prehistoric times.
A group of Viking women build a ship and set off across the sea to locate their missing menfolk, only to fall into the clutches of the barbarian Grimolts who hold their men captive and worship the sea serpent which overturned their ship.
Marine atomic tests cause changes in the ocean's ecosystem resulting in dangerous blobs of radiation and the resurrection of a dormant dinosaur which threatens London.
The Ten Brothers return as the Lake Devil is plagued by a monster fish. To settle the old score, Marshal asks Shrimpy and his ten sons to exterminate the fish. Excelled on land, the ten brothers find themselves quite useless in the water.
A crook decides to bump off members of his inept crew and blame their deaths on a legendary sea creature. What he doesn't know is that the creature is real.
Two strongmen set out to hunt down a murderous sea monster. Their ship is wrecked and they end up in the Holy Land where Hercules is assumed to be Samson who is a wanted man. The two team up to survive.
When a mad scientist begins kidnapping wrestlers and extracting their spinal fluid to create a race of Gill Men, two cops call in Batwoman to investigate. But when her mission leaves the scientist horrifically scarred, he seeks revenge.
An eclectic group of characters set sail on Captain Lansen’s leaky cargo ship in an attempt to escape their various troubles. When a violent storm strikes, the ship is swept into the Sargasso Sea and the passengers find themselves trapped on an island populated by man-eating seaweed, giant crabs and Spanish conquistadors who believe it’s still the 16th century.
Scientists pursuing the mysteries of the deep are threatened by a beautiful girl who seems to have returned from the dead and by a prehistoric sea creature that dwells in the deadly Bermuda Triangle.
Searching for the lost world of Atlantis, Prof. Aitken, his son Charles and Greg Collinson are betrayed by the crew of their expedition's ship, attracted by the fabulous treasures of Atlantis. The diving bell disabled, a deep sea monster attacks the boat. They are all dragged to the bottom of the sea where they meet the inhabitants of the lost continent, an advanced alien race that makes sailors their slaves.
A nuclear leak creates a mutant Slithis sea monster, which terrorizes the variety of pets, winos, and hippies who hang around Venice, California.
Little coastal town is being terrorized by deadly Barracudas.