The Haunted Lake by P.J. Lynch

A ghostly love story set in a spooky, underwater world from the highly acclaimed author and illustrator P.J. Lynch. Jacob's father was a farmer, but after their river is dammed and their town is flooded, Jacob takes to fishing the new lake over the town.

A village girl falls in love with him, and he with her. A year before they're to be married, Jacob disappears into the lake, lured underwater by the ghosts who inhabit the sunken village. For fifteen years, his fiancee fishes the lake and searches for her love while Jacob lives, unaging, with the ghosts.