Island of the Fishmen

Island of the Fishmen Lisola degli uomini pesce is a 1979 Italian adventure action horror film directed by Sergio Martino.

Amandas father, Professor Ernest Marvin Joseph Cotten, a oncefamed biologist, has discovered a way to transform humans into amphibious creatures and controls their every move. Rackham manipulates Marvin into performing the procedure upon both willing and unwilling participants by assuring him that his work is undertaken for purely scientific and humanitarian motives Marvin hopes to reduce strain on the world food supply by creating a race of people who can live in the resourceuntapped ocean. Having discovered the lost city of Atlantis beneath the waters surrounding the island however, Rackham is in actuality using the halfhuman monsters to plunder the lost city of its treasures.Shakira Beryl Cunningham, a voodoo priestess in the employ of Rackham foretells death and destruction descending upon the island. ........

Source: Wikipedia