The sea fairies Trot and cap'n bill series, book 1.

This delightful underwater fantasia from Wizard of Oz author L. Frank Baum is sure to enthrall younger readers-and any parents or grandparents who happen to come along for the ride. A little girl named Mayre Griffiths wishes desperately to catch a glimpse of a mermaid. Not only is her wish granted, but she is also invited to pay a visit to the enchanted kingdom of these beautiful creatures.