Soul of the Sea(2009)
A novel by Alison Paige
" The perfect pearl, a sea's soul, given by her true mate, can bind a mermaid to the man and the sea forever. Marina never wanted to be bound to anything. But then she meets Michael Sandbar, a human she can't resist and can only have if she gives up everything she never thought she wanted. There's no place Michael Sandbar would rather be than the open water hoping his childhood fantasy love, a mermaid he saw years ago, isn't a fantasy at all. But when he meets Marina, he'll have to risk everything, body and soul, to have her."