Allen Mountain is located in Essex County, New York. It is part of the Marcy Group of the Great Range of the Adirondack Mountains, and is flanked to the north by Mount Skylight.

Allen Mountain
Allen Mountain summit
Highest point
Elevation	4,347 ft (1,325 m)[1]
Prominence	640 ft (200 m)[1]
Parent peak	Mount Skylight[1]
Listing	Adirondack High Peaks 26th
Coordinates	44°04′15″N 73°56′23″W / 44.07083°N 73.93972°W / 44.07083; -73.93972[2]
Geography
Allen Mountain Location of Allen Mountain within New York Show map of New York Adirondack Park Allen Mountain Allen Mountain (the United States) Show map of the United States
Location	Keene / North Hudson, Essex County, New York
Parent range	Marcy Group of the Great Range
Topo map	USGS Mount Marcy

The south side of Allen Mountain drains into White Lily Brook, thence into the Boreas Ponds, the Boreas River, the Hudson River, and into New York Bay. The southwest side drains into Dudley Brook, thence into the Opalescent River, and the Hudson River. The northwest side drains into Allen Brook, thence into Skylight Brook, and Dudley Brook. The northeast side drains into Marcy Brook, thence into Stillwater Inlet, Upper Ausable Lake, and the Ausable River, which drains into Lake Champlain, and ultimately into Canada's Gulf of Saint Lawrence. The east side drains into Sand Brook, and thence into Stillwater Inlet.

Allen Mountain is in the High Peaks Wilderness Area of Adirondack State Park and was named for Frederick B. Allen (1840–1925) in 1869.

Many experienced hikers in the area consider Allen Mountain to be the most difficult to climb of the 46 Adirondack High Peaks.