Big Indian Mountain is a rugged peak in the central Catskills of Ulster County, New York, within the Big Indian–Beaverkill Range Wilderness Area of Catskill State Park. Surrounded by nearby mountains including Eagle, Fir, and Doubletop, it is notable for its position near a divide between two major drainage systems. Water from its northeast slopes flows by way of Elk Bushkill to Esopus Creek, the Hudson River, and New York Bay, while runoff from its north, west, and south sides enters brooks that feed the Delaware watershed through Dry Brook and the Neversink River. It remains part of a protected wilderness landscape.