"The Black Kiss" is a short story by Robert Bloch and Henry Kuttner. The story, which first appeared in Weird Tales in June 1937, tells of the thing that swam in the black waters off California. It is notable, in that it's the second story by Kuttner to feature the occultist, Michael Leigh (the first, being THE SALEM HORROR which you can find over on HB's YouTube channel: https://www.youtube.com/watch?v=94sW00FhX48&t=0s)