Amphibian Man
Человек-амфибия (original)
People living in a seaside town are frightened by reports about an unknown creature in the ocean. Nobody knows what it is, but it's really the son of Doctor Salvator. The doctor performed surgery on his son and now young Ichtiandr can live underwater. This gives him certain advantages, but creates a lot of problems.
Starring Vladimir Korenev, Anastasiya Vertinskaya, Mikhail Kozakov, Anatoliy Smiranin, Nikolai Simonov, Vladlen Davydov, Yuri Medvedev, Aleksandr Zakharov
Watch "Amphibian Man" on Amazon released in 1962. It's a drama and action & adventure movie, and has a rating of 7 out of 10 from Imdb which is usually fine for this kind of movie, and is currently only available for purchase or rent.