The most common trail used to Summit Mummy Mountain is the Lawn Lake Trail. To get to this trailhead, enter the National Park through the Fall River Entrance, Hwy 34. About 2 miles into the park, take a right where the signs point you to "Old Fall River Rd." and "End o' Valley." Once on this road, you will take your first right, where signs clearly point you to the "Lawn Lake Trailhead."
Follow the well established trail for 6.3 miles to Lawn Lake.
From Lawn Lake, continue up the trail leading to the tundra directly in front of you (NW) toward the head of the valley. The trail winds through willows and over a few streams until you finally reach the edge of treeline. Keep going until you reach the junction for the trail to Crystal Lakes and the trail to "The Saddle." There is a very visible and well marked sign here.
Follow the trail toward The Saddle. Just a couple of hundred yards from this sign, look uphill to your right (north). There are probably a hundred different lines you could use for your ascent....pick the best/most fun/most challenging/easiest/etc..etc.. one. This section is nothing more than class 2+....I used my hands some for balance, but didn't really need to use hand holds much at all.
You need to get high on the ridge above you and head east (right) toward the summit of Mummy Mountain.
There wis a flat and wide slope leading up to final and steep summit push. Again, pick your way up this final slope as you see fit. The way I chose was definately some class 3 terrain, but if one stayed along the crest of the ridge, this could be a walk up.
Near the summit, a little boulder hopping is required, before the summit cairn comes into view. Take adavantage of the incredible views back down to Lawn Lake and the views to the north!
There is no trail once you leave it above the Crystal Lake junction. But from there it is pretty straight forward.
Nothing other than your typical dayhiking gear. Bring plenty of water, or a filter, as you are away from water for quite some time. In the winter, snowshoes would be neccessary, and you may want some crampons for this route. You could probably leave the axe at home.