“I arrived at another hall, the roof of which was of a pale blue, spangled with constellations of silver stars, and supported by porphyry pillars of a paler red than ordinary. The whole of the floor of this hall, except a narrow path behind the pillars, paved with black, was hollowed into a huge basin, many feet deep, and filled with the purest, most liquid and radiant water. The bottom was paved with all kinds of refulgent stones, of every shape and hue. Led by an irresistible desire, I undressed, and plunged into the water. I rose to the surface, shook the water from my hair, and swam as in a rainbow, amid the coruscations of the gems below seen through the agitation caused by my motion. Then, with open eyes, I dived, and swam beneath the surface. And here was a new wonder. For the basin, thus beheld, appeared to extend on all sides like a sea, with here and there groups as of ocean rocks, hollowed by ceaseless billows into wondrous caves and grotesque pinnacles. Around the caves grew sea-weeds of all hues, and the corals glowed between. I thought I had been enchanted; and that when I rose to the surface, I should find myself miles from land, swimming alone upon a heaving sea; but when my eyes emerged from the waters, I saw above me the blue spangled vault, and the red pillars around.”

— Phantastes, by George MacDonald

“‘Down there,’ said Golg, ‘I could show you real gold, real silver, real diamonds.’

“‘Bosh!’ said Jill rudely. ‘As if we didn't know that we're below the deepest mines even here.’

“‘Yes,’ said Golg. ‘I have heard of those little scratches in the crust that you Topdwellers call mines. But that's where you get dead gold, dead silver, dead gems. Down in Bism we have them alive and growing. There I'll pick you bunches of rubies that you can eat and squeeze you a cup full of diamond-juice. You won't care much about fingering the cold, dead treasures of your shallow mines after you have tasted the live ones of Bism.’”
— C.S.Lewis, “The Chronicles of Narnia: The Silver Chair”, Chapter 14, “The Bottom of the World”