The Moon Pool (Unabridged‪)‬

Dr. David Throckmartin’s scientific expedition to the South Sea Islands discovers among ancient ruins a portal into Muria, an unknown underground world. After the disappearance of Throckmartin, his wife and two companions, his old friend Dr. Walter Goodwin enters Muria with a rescue party, only to confront an fantastic world filled with incredible beings, astounding scientific advances, and the worship of the most evil of all creatures, The Dweller.