The Atlantic Abomination, by John Brunner

I didn't have high hopes for this book, but I heard there might be some Lovecraftian elements. In the sense that a big monstrous being with some powers of mind control was in hibernation deep under the water and gets woken up by the sciences straining too far in one direction, yes it is Lovecraftian. But in any real sense, it is not Lovecraftian. John Brunner wrote many great novels; this is not among them.

Favorite moment: male scientist hero type assumes that attractive female scientists without boyfriends must have something seriously wrong with them. Fortunately, he overcomes this prejudice and marries attractive female scientist.

Anyway, go read Stand on Zanzibar.