The trailhead is located across the Going-To-The-Sun-Road from the Avalanche Campground at The Trail of the Cedars.
The trail actually begins as part of the Trail of the Cedars which winds through spectacular virgin stands of hemlock and western red cedar. Most of the trail is actually a boardwalk through the boggy woods. The forest is quite old, determined to have last suffered a fire in the early 1500s!
About a tenth of a mile, the trail breaks off to the right (just past the Gorge). Stay left at the next intersection to head up to the lake. Avalanche Lake Trail starts to ascend as soon as you leave the Trail of the Cedars. Total gain between the boardwalk and Avalanche lake is 500 feet. Actual altitude change on the rolling trail is closer to 1,000 feet.
A short climb later you come to a bit of a clearing where you can hear, and if you aren't afraid of heights, look over the edge at Avalanche Creek. If you stay on the trail you are plenty far away from the edge.
Near the lake the trail breaks out of the trees and you can see Bearhat Mountain on your left that forms the east wall of the valley while the west wall is formed by Mount Brown.
When you get to the lake you can't help but stop and look across at the huge cliffs across the way. Glacier water and lake water creates some of the most beautiful waterfalls (where some of them merge is called Monument Falls) cascading down to the lake from the hanging cirque valley formed by Sperry Glacier, which cannot be seen from the lake.
For those of you lucky enough to get to Avalanche Lake on a warm day soon after the trail opens in May, you will be treated to the sights and sounds of many avalanches, which is quite a sight if you have never seen one up close before.
WARNING! Hiking and outdoor related sports can be dangerous. Be responsible and prepare for the trip. Study the area you are entering and plan accordingly. Dress for the current and unexpected weather changes. Take plenty of water. Never go alone. Make an itinerary with your plan(s), route(s), destination(s) and expected return time. Give your itinerary to trusted family and/or friends.