Trying to remember a title...

[H.]

I read this book five or six years ago, about a guy who's sent to a remote island to be a lighthouse keeper or something similar, to take over from another guy who'd gone crazy/degenerate because of this woman from a kind of...mutant sea-people population? And the protagonist gets obsessed with her and has the same kind of mental degeneration... Does that ring any bells for anyone?

[Gregor]

It sounds like it was inspired by Lovecraft's "Dagon."

[Latasha]

no sorry, but it sounds good! if you remember the name I'd love to know so I could read it too.

[MJ]

Definitely sounds like Dagon.