On a volcanic island near the kingdom of Hetvia rules Count Dakkar, a benevolent leader and scientist who has eliminated class distinction among the island's inhabitants. Dakkar, his daughter Sonia and her fiance, chief engineer Nicolai Roget, have designed a submarine boat which Roget pilots on its initial test voyage shortly before the island is overrun by Baron Falon, once Daggar's friend, and now the new despotic ruler of Hetvia. The Baron has Dakkar and his daughter tortured so that Dakkar will reveal all his discoveries. Dakkar is able to escape with the intervention of his loyal men. But Falon sets out after Roget and Dakkar using the Count's second submarine. The two underwater craft dive very deep to the ocean floor, where they discover a strange land populated by dragons, a giant octopus, and eerie, undiscovered humanoid race.

• Lionel Barrymore as Count Dakkar
• Jacqueline Gadsden as Sonia Dakkar
• Lloyd Hughes as Nikolai Roget
• Montagu Love as Falon
• Harry Gribbon as Mikhail
• Snitz Edwards as Anton
• Gibson Gowland as Dmitry
• Dolores Brinkman as Teresa
• Karl Dane (uncredited)
• Robert Dudley as Workman (uncredited)
• Angelo Rossitto as Underwater Creature (uncredited)
• Carl 'Major' Roup as Underwater Creature (uncredited)
• Billy Schuler (uncredited)
• Pauline Starke (uncredited)
• Jack Stoutenburg (uncredited)
• Harry Tenbrook as Workman (uncredited)
• Robert McKim (uncredited)

The film had a budget of $1,130,000.^[2] According to an article in the original Famous Monsters of Filmland magazine, production was actually started in 1926. There were various problems, including weather and the advent of talkies, which slowed/halted production several times before the film was finally completed and released three years later. The article included stills showing the original 1926 undersea denizens and the redesigned version which actually appeared in the film. Footage directed by Maurice Tourneur and Benjamin Christensen in 1927 was incorporated into the final 1929 version.

The film is loosely based on the back-story given for Captain Nemo in the novel The Mysterious Island, and might more properly be thought of as a prequel to Twenty Thousand Leagues Under the Sea. It is the story of Count Dakkar (Captain Nemo's real name is revealed to be Prince Dakkar in The Mysterious Island), how he built his submarine, how he was betrayed, and how he became an outcast seeking revenge.

The film's financial failure cost MGM $878,000.^[2]

Until recently, only one reel with a color sequence was thought to have survived, in the collection of the UCLA Film and Television Archive.

In 2013, Deborah Stoiber from the George Eastman House film archive visited Prague to examine the sole existing color copy of The Mysterious Island. The U.S. film experts, in cooperation with the Czech National Film Archive, restored the color print of The Mysterious Island.^[3] After the complete Technicolor print was discovered in Prague in December 2013, a new print of the film premiered at the 33rd Pordenone Silent Film Festival in October 2014.^[4]

The film is available March 26, 2019 on MOD from Warner Archive collection, but only in an unrestored black and white print.^[5]

• List of early color feature films
• List of early sound feature films (1926–1929)
• List of underwater science fiction works
• Lionel Barrymore filmography

• Medved, Harry; Medved, Michael (1984). The Hollywood Hall of Shame: The Most Expensive Flops in Movie History. Angus & Robertson. ISBN 0207149291.

• The Mysterious Island at IMDb  
• Synopsis at AllMovie
• The Mysterious Island at the TCM Movie Database
• The Mysterious Island at the American Film Institute Catalog
• Lantern slide (archived)
• Early Technicolor discoveries from the BFI National Archive on YouTube (The Mysterious Island screen test at 4:12)