OK! The mermaids of the title here are actually pearl divers who require Tarzan's help to topple their evil leader. Oh and said evil leader has set himself up as a false God, thus enslaving the islanders with religious fervour.
Filmed at Churubusco Studios in Mexico, Mermaids is the final appearance of Johnny Weissmuller as Tarzan. It's no great send off for the man who had worn the loin cloth with distinction. It's standard fare, with the franchise looking as tired as its iconic lead actor. However, it moves along at a good clip, introduces us to the lovely Linda Christian and director Robert Florey inserts enough under water battles (with men and creature) and cliff diving escapades to keep the pic zippy. Boy is away in England studying, but Jane (Brenda Joyce) is around looking delicious and not at all jealous of Tarzan bringing home Mara (Christian) after she escapes a planned marriage to evil false deity guy. While Cheeta, bless her, auditions for the role of Duane Eddy.
Harmless lord of the apes fluff all told, but instantly forgettable into the bargain. 6/10