The moon pool.

"On the island of Ponape in the South Pacific, the cold light of a full moon washes over the crumbling ruins of an ancient, vanished civilization. Unleashed from the depths is the Dweller, a glittering, enigmatic force of monstrous terror and radiant beauty that stalks the South Pacific, claiming all in its path. An inter-national expedition led by American Walter Goodwin races to save those who have fallen victim to the Dweller.

The dark mystery behind the malevolent force is Muria, a forgotten, mythic world deep within the earth that is home to a legendary people intent on reclaiming what was theirs long ago. This commemorative edition of The Moon Pool features an introduction by Robert Silverberg, a review of the first edition, and a glossary of the Murian language."--BOOK JACKET.