ALLEN MOUNTAIN
via East River Trailhead
Sitting alone in the southern High Peaks, Allen Mountain is the longest out-and-back hike of any stand-alone Adirondack 46er. Its remote location, combined with an unmarked and difficult herd path, makes this hike a true test of endurance and navigation skills. While not technical, the sheer length, remoteness, and lack of trail markings have earned Allen a reputation as one of the most grueling of the 46. Those attempting this peak should be physically prepared and, if possible, hike with someone who has done Allen before.
What to know
Start:
East River Trailhead
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Elevation Gain:
3,600 feet
Summit Elevations:
Allen Mountain 4,340 feet
Trail Length:
19.6 miles round trip
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Difficulty:
5 out of 7 - Very Difficult
Average Hiking Time:
12–14 hours
View Type:
Summit is in the trees, however a nearby spur trail offers breathtaking views of the Great Range, Panther Gorge, Skylight, and other surrounding peaks from a spur trail.
Dog Friendliness:
Not the best hike for dogs, but fine if your dog is used to this kind of outing.
Trail Surface:
Long, rugged, muddy, and wet. Herd paths are unmarked and challenging.
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Water Availability:
Water can be found at the Opalescent River and Skylight Brook to filter.
Maximum Grade:
1,050 feet in 0.5 miles—upper half of Allen Mountain ascent.
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Sunrise or Sunset:
Not recommended due to long approach and navigation difficulty.
Special Considerations:
This hike can be done as an overnight when primitive camping. Go with a friend, and expect it to be long and hard. If you have bad footwear, bring microspikes for the slide up Allen. It’s very slimy. This route involves a mix of unmarked herd paths, overgrown areas, and river crossings, with challenging, steep climbs and slippery, eroded sections, demanding careful navigation. This can not be done in high waters.
DO NOT TAKE any other route on the map. The surrounding logging roads are not faster.
Intro
Allen Mountain is one of the most isolated 4,000-footers in the Northeast, standing alone in the southern High Peaks. The mountain was named in 1869 after Reverend Frederick B. Allen, an Episcopal minister. Unlike other High Peaks, Allen was not climbed until 1921, when Robert and George Marshall and their guide, Herbert Clark, made the first recorded ascent. Historically, Allen was most commonly climbed from the east, but today, it is almost exclusively hiked from the west due to modern access points. The rugged terrain and extensive approach make it one of the most challenging of the 46.
The Hike
After passing the lake, the trail remains wide and easy to follow. About 0.3 miles later, you will pass an abandoned fire tower ranger shack on the left. Shortly after, at 1.2 miles, you will pass the Mount Adams Trail turnoff on the left, marked by a sign. Continue straight past this point. The next 0.5 miles consists of muddy, uneven terrain before you reach Lake Sally at 1.8 miles. As you approach, there will be another logging path intersection; stay left here.
The trail then parallels Lake Sally for 0.4 miles before continuing through level forest for another 0.3 miles, reaching another logging road junction at 2.7 miles. Here, the path merges onto another old road, and once again, you will stay left. Over the next 1.4 miles, the trail becomes easier, remaining relatively flat as it winds through open marshland and mixed forest. Along this stretch, you will get your first distant glimpse of Allen Mountain.
The trail begins with a pleasant walk through the woods on a fairly wide path. After a few hundred yards, it bears right at the Hudson River, following it for a short distance before reaching a metal suspension bridge. This bridge, damaged by high waters in 2019, has not been replaced and remains somewhat lopsided, requiring careful footing as you cross. After making it over the bridge, the trail continues for another 0.3 miles until you reach Lake Jimmy.
Pay close attention here, as the trail eventually veers left into the woods. If you continue straight, you will hit a dead end where an old bridge once provided a crossing before it was removed in 2011. Some debris now blocks this area, making the correct path more obvious. Follow the herd path left, winding around the lake in a clockwise direction. This section includes boardwalks and marshy terrain before reconnecting to the main trail on the other side.
At 4.1 miles, you will arrive at the Opalescent River crossing, which presents one of the biggest challenges of the approach. A bridge once stood here but was washed away in 2019. If water levels are low, you can rock-hop across where the bridge used to be, but if the river is high, you may need to find a suitable crossing farther downstream. There is a 50-50 chance of getting across without getting wet, though if water levels are high, you may have to remove your boots and socks to ford the river.
Once across, the trail enters denser woods and becomes rougher. Over the next 1.2 miles, it remains relatively easy to follow, winding through marshy areas and crossing another smaller stream before reaching the East River Trail junction to Lake Colden at 5.2 miles. Continue straight, following a rugged but defined trail through mixed terrain.
At 5.7 miles, the trail intersects with a larger old logging road. Turn left onto this road briefly before turning right onto an older ranger trail. At 5.8 miles, you will reach an old parking lot, which marks an important waypoint. From here, you are 2.8 miles from the base of Allen. The next stretch of the hike features more varied terrain as you navigate through sections of rough, overgrown woods and open hardwood forest with dirt and rocky surfaces.
Over the next 2 miles, the trail steadily gains elevation, but this is not yet Allen Mountain. Instead, you will climb over a large rolling hill within the valley. This section includes a gradual 600-foot ascent, followed by a 200-foot descent on the other side. Navigation in this area can be tricky due to the lack of official trail markers, so stay vigilant and retrace your steps if needed. The trail eventually crests the hill and drops into a wooded ravine before reaching a small river crossing.
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About 0.1 miles after this crossing, you will arrive at Skylight Brook at 8.0 miles. This is the final major water source and a great place to refill before the steep ascent to the summit. The trail follows Skylight Brook uphill for 0.5 miles before veering right, leading to the base of Allen. The true base of the mountain is marked by a flat-walled waterfall, an obvious feature that signals the beginning of the final climb. From this point, the summit is only 1.2 miles away, but the final push includes a relentless 1,600-foot ascent. This is where the real challenge begins. Expect the ascent to take around an hour, with wet, slippery conditions along much of the route. The trail follows Allen Brook, which means constant exposure to flowing water, mud, and slick rock. Be prepared for frequent rock scrambles, deep mud pits, and large tree roots that will require careful navigation.
Around 70 percent of the way up, you will reach the infamous Allen Mountain slide. The exposed rock here is covered in wet red algae, making it extremely slippery. Choose your footing carefully, stepping only on dry areas and using nearby trees for balance. Halfway up the slide, the trail crosses from one side to the other. Though challenging, this section offers excellent views of the Santanoni Range and the long approach you’ve traveled. Once at the top of the slide, the trail re-enters the forest and remains incredibly steep. A few short but demanding scrambles will require you to rely on surrounding vegetation for support. Eventually, the trail begins to level out, offering the first clear views of the summit ahead.
For the final approach, the trail turns left and follows a narrow ridge toward the summit. Just before reaching the top, there is a great viewpoint looking west toward the High Peaks. The last section includes a 40-foot climb over the "nubble" of Allen, bringing you to the official summit. The summit itself is marked by a yellow sign but has little in the way of open views. In winter, deep snow can bury the sign, reducing it from 7 feet high to just a few inches above the surface. However, a short herd path beyond the summit leads to a much better viewpoint, where you can see the entire Great Range, Skylight, Panther Gorge, and many other surrounding peaks. After soaking in the view, retrace your steps for the long 9.8-mile journey back to the East River Trailhead.
Trail Summary
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0.0 Start at East River Trailhead.
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0.1 Turn right at Hudson River, and cross metal suspension bridge.
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0.5 Trail turns left into woods near Lake Jimmy.
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0.8 Reach other side of Lake Jimmy.
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1.2 Pass abandoned ranger shack and Mount Adams Trail, and continue straight.
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1.8 Turn left at logging path fork, arriving at Lake Sally shortly after.
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2.7 Reach another logging path junction, and stay left.
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4.1 Cross Opalescent River.
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5.2 Pass the East River Trail to Lake Colden, continuing straight.
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5.7 Turn left onto a larger logging road, then turn right into an older ranger trailhead.
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5.8 Reach parking lot, and walk to its end.
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8.0 Cross Skylight Brook.
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8.5 Reach base of Allen marked by a flat- walled waterfall.
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9.4 Reach Allen Mountain slide.
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9.7 Summit Allen Mountain, following herd path for better views; turnaround.
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19.6 Arrive back at East River Trailhead.
