The "mermaids" are really tribal pearl divers in this diverting Tarzan adventure. Their livelihood is threatened by an evil white trader (Fernando Wagner), who sets himself up as a "god." With the help of lovely diver Linda Christian (later Mrs. Tyrone Power), Tarzan defeats the wicked despot, but not before several underwater battles, not the least of which involves an octopus. If the jungle settings of Tarzan and the Mermaids don't look particularly African, that's because the film was shot at the Churubusco Studios in Mexico. Mermaids represents the final appearance of Johnny Weissmuller as Tarzan.
by Hal Erickson synopsis