From publisher blurb: The campaign world of Pax Lexque expands under the sea! Five underwater realms are detailed in this volume, with their history, geography, politics and religion. Also included are ten new spells and four new classes: Aquatic Elf, Chapod, Deep Hunter, and Merfolk. An adventure for this setting is included in the latter part of this book. In Mother of Pearls, the king of the aquatic elves, King Ascal, has been attacked by a race of fish men known as the ichtharians. The party must find the king's crown and deal appropriately with the thieves.