Surrender to the Sea (Lords of the Abyss Book 4) by Michelle M. Pillow

Atlantes, a lost city of intrigue to most, is Brutus's home, his curse, his prison. Doomed to an immortal life deep in the ocean, their only chance at salvation is to rescue damsels in distress from the surface world and bring them into the abyss. While mythology may label he and his kind monsters, this warrior is simply a man with needs. And he's found the perfect woman to see to them.