Sinbad the Sailor (Kerwin Matthews) and his crew land on the island of Colossa, where they meet Sokurah the Magician (Torin Thatcher) trying to escape from a giant Cyclops. Sokurah escapes but loses his magic lamp. He asks Sinbad to help him get it back, but Parisa, Princess of Chandra (Kathryn Grant) is aboard. Their marriage will mean peace between her father’s realm and Sinbad’s Baghdad.

At the pre-wedding, Sokurah turns Parisa’s handmaiden Sadi (Nana de Herrera) into a serpent-like being. The Caliph also refuses to help Sokurah, so he shrinks the princess, enraging her father, the Sultan of Chandra (Harold Kasket), who declares war on Baghdad. Sinbad and the Caliph have no choice but to give in. Sokurah says they need the eggshell of a Roc to restore her, and that is available only on Colossa. Sokurah gives Sinbad the plans for a giant crossbow for the monsters.

Sinbad adds to his crew from the Caliph’s prisons. Led by Karim (Danny Green), they mutiny and capture Sokurah, Sinbad, and his men. During a storm, the cries of demons drive the crew close to madness. Sinbad is released and Karim falls to his death. On Colossa, Sinbad, Sokurah, and six of the crew enter the Valley of the Cyclops. Followed by Harufa (Alfred Brown), Sinbad’s loyal aide, Sinbad and his men find the cyclops’s cave, but are captured and put in a wooden cage. Sokurah steals the lamp and runs away. With tiny Paresi’s help, Sinbad escapes the cage, blinds the Cyclops, and lures it off a cliff. Sinbad seizes the lamp and decides to hold onto it until Parisa is restored.

Sokurah leads them to the nesting place of the giant Rocs. The starving men open an egg and roast a chick. Parisa enters the lamp and befriends the child-like Genie Barani (Richard Eyer) inside, who tells her how to summon his powers in exchange for a promise of freedom. The Roc returns and starts killing men. Sinbad is dropped into the nest. Sokurah kills Harufa and abducts the princess to his underground fortress.

Sinbad awakens and rubs the lamp. The Genie takes him to the fortress and helps him evade the dragon. Sinbad forces Sokurah to restore the princess. But Sokurah animates a skeleton warrior, which Sinbad defeats. With the Genie’s help, Sinbad and Parisa escape, destroying the lamp by throwing it in a pool of lava, reversing Sokurah’s evil magic and bringing Harufa back to life.

Another Cyclops attacks them, but Sinbad releases the dragon, and they battle. Sinbad and Parisa move on, but Sokurah sics the dragon on them. On the beach, Sinbad’s men handle the giant crossbow, and they kill the dragon, which falls on Sokurah, killing him. They leave for Baghdad with Barusa, now a human cabin boy, though he has filled the captain’s cabin with the Cyclops’s treasure as a wedding gift.

It took Ray Harryhausen eleven months to create the Cyclops, in widescreen and full color. The Cyclops was part Pan, with a horn, goat legs and cloven hooves, based on the Ymir alien from 20 Million Miles to Earth. It was given satyr legs so audiences would not think it was a man in a costume. The swordfight with the skeleton led to the battle scene with the skeletal Earthborn Men in Jason and the Argonauts. The cobra-woman was based on a belly dancer and later became Medusa in Clash of the Titans. The dragon model was three feet long and difficult to animate. They used a flamethrower for its fiery breath.

The music of Bernard Herrmann was probably the best of the Harryhausen movies. Seventh Voyage got 100% on Rotten Tomatoes. This was the first film listed as using what they called Dynamation (dynamic animation), afterward called Superdynamation and Dynarama, all inspired by producer Schneer’s Buick with Dynaflow. La Alhambra castle in Spain, from the 12th and 14th Century, appears in the film. The fistfight aboard the ship uses some audio cues from the Three Stooges. The story is more like a blend of the Third and Fifth Voyages of Sinbad than the Seventh.