Captain Lansen reads the burial rites over a coffin watched by Spanish conquistadors, priests, pirates and seamen. As a coffin is ditched overboard the captain asks "What happened to us? How did we all get here...?". On board the tramp steamer Corita, Captain Lansen ignores a customs launch wanting to inspect his ship as he is smuggling the explosive Phosphor B . His ship's passengers also have various reasons for leaving Freetown: Dr. Webster and his daughter Unity for his indiscretions with patients; an alcoholic conman Harry Tyler ; and Eva Peters, who has stolen bearer bonds to pay for the ransom on her son in Caracas, with lawyer, Ricaldi, after her to retrieve them. An accident nearly sets off the explosives and power is lost. Some of the crew mutiny and take to a lifeboat. Chief Engineer Nick cannot fix the generator and Lansen, fearing the ship may explode, takes the remaining crew and passengers into a lifeboat. Dr Webster is devoured by a shark. The next morning the lifeboat finds itself adrift in carnivorous seaweed, which kills the cook. The lifeboat bumps into the Corita and they find the propellers fouled with the seaweed. During the night, Unity is attacked by a huge octopus, which kills Ricaldi when he attempts to rescue her. Sarah appears walking on the weed, using buoyancy balloons attached to her shoulders. She warns the captain of an impending attack. The crew and passengers defend the ship, with the surviving attackers returning to a Spanish galleon. Child leader "El Supremo", the descendant of the Spanish Conquistadores, along with members of the Spanish Inquisition had ordered the attack to steal supplies. The leader of the failed attack is fed to a sea monster in a pit. Sarah attempts to return to her island but is tracked down by the Spanish. While on a rock, the bartender is killed by a giant crab. Sarah, the ship's chief, and Tyler are then captured by the Spanish and taken to the galleon. Lansen uses the explosives to destroy the galleon and rescue his crew/passengers. Lansen and his crew, along with those Spaniards who have decided to join him, head back to the Corita and we return to the start of the film with the burial of "El Supremo", who, toward the movie's end, tries to save the Lansen party, but is killed by one of his followers: it is later revealed that "El Supremo" is really Eva's son.
Music by Gerard Schürmann and title song by The Peddlers
Special effects by Robert A Mattey
Production
A 175,000 gallon tank was constructed at Elstree Studios to shoot the sea scenes. The credits list Michael Nash — a pseudonym for Michael Carreras — as the screenwriter. The production began under the direction of Leslie Norman, but he was soon replaced by Carreras. Hammer's musical directorPhilip Martell rejected the original film score by Benjamin Frankel and commissioned a new one from Gerald Schumann. This film was one of several Hammer movies that featured unusual characters and prehistoric creatures, following the tradition of One Million Years B.C.. It was rated X when first released.
Reception
According to Fox records the film required $2,025,000 in rentals to break even and by 11 December 1970 had made $1,100,000 so made a loss to the studio.
Soundtrack
The film titles has the song Lost Continent performed by The Peddlers played over them.