Goddess of the Sea by P. C. Cast — book slip

Home alone on the night of her twenty-fifth birthday, Air Force Sergeant Christine Canady yearns for something to cure her loneliness. After drinking too much champagne, she recites a divine invocation to revive her humdrum life. But how was she to know the spell would actually work?

When her plane crashes into the ocean, CC's life changes forever. She awakens, bewildered, to find herself in a legendary time and place ruled by magic—and in the body of the mythic mermaid Undine.

But danger lurks in the waters, ready to swallow CC whole. Taking pity on her, the goddess Gaea turns her into a damsel, that she might seek shelter on land.

But when a dashing knight comes to CC's rescue—a dream-come-true she should be falling for—she instead aches for the sea and the darkly sexy merman who's stolen her heart...