Distance (Round-Trip): 8.4 miles
Elevation Gain: 2398'
Elevation: 9,405' to 11,803'
The trail to Chasm Lake starts off from the Longs Peak Ranger Station and mounts slowly but steadily through a forest of lodgepole, spruce and fir. You will pass the trail heading towards Estes Cone and Eugenia Mine on the right. You continue on the path, following Alpine Brook for a short distance. You cross over a rustic bridge and then move from the sub-alpine forest (at about 2 miles in) to an area with trees that resemble a 'dwarf forest'. As you continue, you arrive in the alpine tundra. At the ridge on Mills Moraine (11,550'), you will find a privy/pit toilet, and a place to attach your stock (which are not allowed further up the trail).
From there, the trail becomes narrower and rockier. You follow the valley side above Peacock Pool - there are quite steep cliffs just below, so pay attention! At the end of the valley, you pass over the Roaring Fork and reach a flat area with a privy/pit toilet. Take the steep path towards the right - the path is no longer well-marked as you go up the rocky incline. You'll do a quick zig-zag, and then arrive at Chasm Lake. There you will see the east face of Longs Peak, called the Diamond.