Big Indian Mountain is a mountain located in Ulster County, New York. The mountain is part of the Catskill Mountains. It is flanked to the northwest by Eagle Mountain, to the southeast by Fir Mountain, and to the southwest by Doubletop Mountain.
The northeast slopes of Big Indian Mountain drain into Elk Bushkill, thence into Esopus Creek, the Hudson River, and into New York Bay. The north end of Big Indian Mtn. drains into Shandaken Brook, thence into Dry Brook, the East Branch of the Delaware River, and into Delaware Bay. The west side of Big Indian Mtn. drains into the headwaters of Dry Brook. The southern slopes of Big Indian Mtn. drain into Biscuit Brook and Pigeon Brook, thence into the West Branch of the Neversink River, and the Delaware River.
Big Indian Mountain is within of New York's Catskill State Park.