Clearbrook has its own private pathway to the heights of the Franconia Range. The original Osseo trail was constructed from logging roads by the North Woodstock Improvement Association in the early part of the century. It began at what was logging Camp 3 at the upper dam on the East Branch, which was reached by hitching a ride on the logging railroad out of Lincoln. In the 1920's the trail was taken over by the AMC, which maintained it until the construction of Clearbrook around 1980. It is now maintained by Clearbrook residents.
The old trailhead parking lot can be seen as a flat area on the left side of the Kancamagus Highway just before the Clearbrook entrance. The trail is now accessed by parking on the gravel patch at the bend in the road between CB20 and 21. There is no indication of the trail from the road, so it may take a moment to find it by looking to the right between the third and fourth boulders as you walk a few yards back down the road. Once on the trail, it is easy to follow. It is a clear, wide path that leads directly to Clear Brook. Aside from hikers, it is used by fly fishermen and a few hunters, who know of deer habitat along its trace.
After a wet spell, the first crossing of Clear Brook can be a problem. If you walk across by stepping on stones, it is a good idea to use a staff on the downstream side to lean against as a third point of support. The trail then follows along the left bank through some wet areas and crosses several smaller streams. This section of the trail is an easy grade extending through red maple, beech and hemlock groves and can be traveled by almost anyone. At about three-quarters of a mile, there is an intersection with a local path that can be used as a loop trail. This path leaves to the left and then circles back by the water tank and comes out in Clearbrook I, where a return can be made over the bridge on the paved connecting way.
Continuing another 100 yards on the Old Osseo Trail, there is a campsite on the right with access to the brook. At a quarter mile past the intersection, there is an old logging camping area at the second crossing of Clear Brook. This is an excellent campsite and always a good spot for a rest. If you are going to the peak of Osseo, this is the last sure water, but there is another smaller stream about a quarter of a mile beyond. Water in both streams is usually cold, clear and potable, but be aware that streams in the wild may harbor parasites. Crossing Clearbrook at this point is sometimes easier a few yards upstream.
On the other side of the brook, the trail is less well traveled but is clearly marked with yellow blazes. For about 100 yards, the trail follows the brook, rising a little above it, then turns sharply to the right through a wet area. It then cuts left across a small brook and then zigzags a bit up a wet hill. It then turns right and crosses a small stream, which usually provides good water, and enters hardwood Beech/Maple growth. The trail then zigzags with increasing steepness in a NE direction for about 30 minutes. This is generally the toughest part of the trail, before it turns right onto a more gently climbing old logging road. When the leaves are off the trees, a good view of Loon can be seen from the slide that crosses this section of the trail after about a quarter mile.
After continuing on for a couple of hundred yards, the trail turns left and ascends steeply for a short way to another old logging road, which passes through the lowest point in the ridge between the southern shoulder of Osseo and Potash Knob. On the ridge, there is a huge overhanging Shelter Rock on the L., where a logging camp formerly existed. This is also a good area for exploring as it is not too steep. Immediately beyond, the trail turns sharply to the L. and ascends more rapidly on a logging road for 5 min, then climbs to the R to a still higher parallel road. At the end of this road, it ascends steep switchbacks to the R around a shoulder and gains, in a few minutes, a little shelf at the base of an apparently inaccessible ledge on the E side of Osseo. Good views are possible out on two side paths to the bottom and side of the ledge. The trail then switch backs steeply skirting the ledge, before it slabs for 5 min under the S. side of the peak. It then turns sharply L up a little ravine, which after a short, stiff climb gains the ridge. Just as the trail gains the ridge, a short side path on the L leads to the edge of a cliff from which there is a good view of Lincoln. At this point the trail turns right (E) and quickly leads to the relatively, flat wooded peak of Osseo. There is a camp area at the peak, which affords limited views looking generally east.
Resuming, the main trail meanders for a hundred yards through thick growth, before taking a straight line N over the ridge. After about 30 min of gradual ascent, the trail comes to the junction with another ridge connecting to the Coolidge Mtns on the west. At this point, there was once a trail running to Big Coolidge Mtn. Continuing N, the trail descends a little, bears to the L for a few minutes and follows the part of the ridge leading toward Flume Mtn, glimpses of which are caught through the trees on the right. The trail then rises to the junction with the (new) Osseo trail, which connects the Wilderness trail with the Franconia Ridge trail leading to the peak of Flume Mtn.
Osseo (Whaleback) Peak is 3640 ft high and is 3 mi or 2 h 30 min from start of the trail. Flume Mtn. is 4328 ft and is about 5.5 mi or 4 h from the start.