The Seven Voyages of Sindbad the Sailor - Sixth Voyage
It struck me as a very strange thing that a river of clear fresh water, which gushed out from the mountain not far from where we stood, instead of flowing into the sea as rivers generally do, turned off sharply, and flowed out of sight under a natural archway of rock, and when I went to examine it more closely I found that inside the cave the walls were thick with diamonds, and rubies, and masses of crystal, and the floor was strewn with ambergris. Here, then, upon this desolate shore we abandoned ourselves to our fate, for there was no possibility of scaling the mountain, and if a ship had appeared it could only have shared our doom. The first thing our captain did was to divide equally amongst us all the food we possessed, and then the length of each man's life depended on the time he could make his portion last. I myself could live upon very little.
Nevertheless, by the time I had buried the last of my companions my stock of provisions was so small that I hardly thought I should live long enough to dig my own grave, which I set about doing, while I regretted bitterly the roving disposition which was always bringing me into such straits, and thought longingly of all the comfort and luxury that I had left. But luckily for me the fancy took me to stand once more beside the river where it plunged out of sight in the depths of the cavern, and as I did so an idea struck me. This river which hid itself underground doubtless emerged again at some distant spot. Why should I not build a raft and trust myself to its swiftly flowing waters? If I perished before I could reach the light of day once more I should be no worse off than I was now, for death stared me in the face, while there was always the possibility that, as I was born under a lucky star, I might find myself safe and sound in some desirable land. I decided at any rate to risk it, and speedily built myself a stout raft of drift-wood with strong cords, of which enough and to spare lay strewn upon the beach. I then made up many packages of rubies, emeralds, rock crystal, ambergris, and precious stuffs, and bound them upon my raft, being careful to preserve the balance, and then I seated myself upon it, having two small oars that I had fashioned laid ready to my hand, and loosed the cord which held it to the bank.