KOKO-NOR, kō'kō-nôr', or KUKU-NOR, a lake in Tibet, not far from the Chinese province of Kan-su, 100° E. and 37° N. It lies 9,975 feet above the level of the sea. Its very salt waters, exquisitely blue in color, cover 66 miles by 40. It is very rich in fish, in spite of the fact that its surface is frequently frozen for two to three months. It contains five islands, one with a Buddhist monastery. In the west it receives the waters of the river Buhaingol. In the south it is bordered by the southern part of the Kokonor Mountains (10,000 feet).