Primary Route
Allen Mountain via East River Trailhead
Standard Route
Allen Mountain is the longest stand-alone Adirondack 46er out-and-back, a remote southern High Peaks objective reached by a long East River approach, multiple water crossings, and a steep unmarked climb beside Allen Brook.
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Route map
Allen Mountain via East River Trailhead
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Planning use
Use the route line and GPX as planning aids. Carry a physical map and verify current official conditions before relying on any route.
Open the Interactive 46 High Peaks MapRoute History
Allen Mountain stands alone in the southern High Peaks and is one of the most isolated 4,000-footers in the Northeast. The mountain was named in 1869 for Reverend Frederick B. Allen, an Episcopal minister. Unlike many other High Peaks, Allen was not climbed until 1921, when Robert Marshall, George Marshall, and guide Herbert Clark made the first recorded ascent. Historically, Allen was more commonly climbed from the east, but today it is almost always climbed from the west because of modern access.
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Route Overview
Allen Mountain via East River Trailhead
The Allen route starts at East River Trailhead, crosses the Hudson, reroutes around Lake Jimmy, passes Lake Sally, crosses the Opalescent River, reaches Skylight Brook, climbs the unmarked Allen Brook slide route, and returns the same way.
Selected Route Access
Use the standard East River Trailhead route. Do not take surrounding logging roads that appear shorter on maps; they are slower, rougher, more confusing, and not the intended Allen approach.
Selected Route Caution
Allen should not be attempted in high water. The route includes the Hudson crossing area, the Opalescent River crossing, wet and overgrown approach sections, and the slick red algae Allen slide. Microspikes can help some hikers on the slide when footwear traction is poor, but judgment and conditions matter more than gear.
Selected Route Guidance
Full guide collapsed for quick scanning. 8 sections available.