Found: Book about man made to feel guilty

What I remember from the book (I think I read it as a teen) was that the cover was creepy: a woman's face that was distorted by what seemed to be a mask. The woman was on the beach. Also, the main male character thought he had been unable to save this girl (who I believe was named Joyce) and felt incredibly guilty about it. However, it turns out people were trying to make him blame himself and Joyce was actually alive. Thank you in advance with all of these posts!

Additionally, Joyce was presumably drowned.

Or maybe her name was not Joyce, but he was made to think that he was responsible for the drowning and was haunted by her.

I believe it was "High Tide" by R. L. Stine.

Stine, High Tide

Thanks for coming back to tell us, people often don't and we're left to guess and guess ...