"The nightmare corpse-city of R'lyeh…was built in measureless eons behind history by the vast, loathsome shapes that seeped down from the dark stars. There lay great Cthulhu and his hordes, hidden in green slimy vaults.” — H.P. Lovecraft, The Call of Cthulhu
R'lyeh is the ancient undersea city in which "dead Cthulhu waits dreaming". It raises above the water when the "stars are right", awakening Cthulhu in the process. The geometry of R'lyeh is said to be non-Euclidean, which means that parallel lines curve away or towards each other. It is located in the southern Pacific Ocean
at 47°9'S 126°43'W, close to the Pacific Pole of Inaccessibility (the point in the ocean farthest from any land).