.. and now that you've reminded me ... I think it was the forerunner of "Jaws" ... because, as in Jaws ... there is a scene (or more?) of the beautiful girl swimming and the camera shoots up from below (first glimpse at a woman's below waist torso) ... and the creature ... J u s t out of reach, but going for her.
Brrrrrr.
I watched about 1/2 of Jaws ... and I will NEVER see it again. There is nothing more helpless than a human in deep water being stalked/attacked by a sea creature.
OK ... back to the skunk ape ....
Kucinich!
A close relative of my Brother-in-law, his name was Ricou Browning or something similar, was the professional diver who played the creature from the Black Lagoon.