The south face of Granite Peak has confused and mystified many people in the past and rightly so. It is a complex face with many ridges, gullies and slabs of varying sizes. Depending on your ability level, there are probably dozens of ways one could reach the summit via this face, however the easiest route will be described here, known as the SW Couloir (or SW Ramp...see below). This route is even quickly becoming the standard route for Granite Peak due to the easier terrain encountered higher on the mountain and the more enjoyable approach. Unfortunately this route also has a decent amount of loose rock and could be considered more dangerous than the "standard" Froze to Death Plateau/East Ridge Route, which is a very enjoyable scramble on excellent rock. Although it is still currently less popular than the standard route, it won't be long before this becomes the most popular route on the mountain. The approach for this route is by far the most beautiful way to reach the mountain. Although the Huckleberry Creek Approach is also fantastic, and both are better than the Froze to Death Plateau approach, the hike past Aero Lakes or Rough Lake into the Sky Top Lakes basin is unsurpassed. If you like fishing bring your rod too!
Allow two days for the trip, plus a day to sit out bad weather if necessary. One way distance from trailhead to summit, depending on your exact route (much of this route is off-trail) is about 13-14 miles. The entire approach is scenic and wild. It features alpine meadows bursting with flowers in the summer, extensive boulder hopping, a couple long hills, and more than one significant stream crossing. Come prepared as it will excite you, but also wear you out! Also be aware that although this route is easier than the east ridge, it is no walk in the park. People attempting this route should be proficient, and prepared for steep loose rock, and steep snow.
Getting to this trailhead seems to be the most difficult piece of route finding but it is actually quite simple. On my main Granite Peak page I named this the Aero Lakes Trailhead but many people call it the Lady of the Lake Trailhead. You start the approach here, which is just a few minutes away from the tiny town of Cooke City between Gardner and Cody. See the map below for the route to the trailhead.
From Cooke City, drive east on US Highway 212 (Beartooth Highway) a little less than 2 miles to the Lulu Pass Road and turn left (north). Go roughly 2.3 miles (mostly gravel) to a large, signed junction (Goose Lake junction), and turn sharply right onto a short dirt road. Continue on this rough, rutted road (but still passable for most cars) for a quarter mile to its end at a small mining cabin with mining relics scattered around. There is room for about 6-8 cars here to park next to the old mining cabin. To get to the actual start of the trail, walk around the cabin on the left side (passing an old hot water heater) and cross a small stream on some boards or rocks. Emerge from the bushes and onto the trail after a few feet of bushwhacking and walk northeast on the trail passing a large sign for Lady of the Lake.
AERO LAKES APPROACH
From the lower trailhead, there is a large cabin nearby just to the east. Walk around it on the left side (passing an old hot water heater) and cross a small stream on some boards or rocks. Emerge on the trail after a few feet of bushwhacking and walk northeast on the trail passing a large sign for Lady of the Lake. The first part of the trail heads up a short steep section and mellows to a nice undulating hike through sparse forests reaching the south end of Lady of the Lake at 8,750 feet after 1.5 miles. Follow the trail around the west side of this large lake (with great fishing and camping) and reach the junction with the trail coming down from the upper trailhead after another mile. A large cairn marks this junction. Continue straight and pass around a large meadow and cross a small creek which flows back down to Lady of the Lake. Don't follow this creek as it curves back to the south. Utilize rocks and logs to get across, then stay on the trail heading up through some trees and reach an obvious (but unsigned) trail junction 0.5 mile from the creek crossing. A few logs block a trail heading straight, however this trail is the route for the Sky Top Creek Approach described below. I will call this trail junction the Tri-Creek junction since it's where Zimmer Creek, Star Creek, and Sky Top Creek converge to form the Broadwater River. For the Aero Lakes route, you want to take the left trail. Your first views of Mount Zimmer and Iceberg Peak are found here to the north. A few minutes beyond the Tri-Creek junction, cross Star Creek a few feet before it dumps into Zimmer Creek and continue up the trail which follows the west side of Zimmer Creek for another mile. When the trail once again reaches the creek side, cross it on a couple large logs at 9,150 feet and locate the trail heading northeast towards Aero Lakes. This junction is unsigned so don't miss it and continue up Zimmer Creek. The trail quickly begins to climb steeply for 900 feet up what is known as heartbreak hill, reaching Lower Aero Lake after another 1.1 miles at 10,000 feet. The final quarter mile to the lower lake is hard to follow, just follow large talus through an obvious gap and descend 50 feet to the lake shore.
Here at the lower lake, the official trail ends (5.4 miles from the TH) but a boot path heads west around the lake, reaching its southwest corner after 0.3 miles which has a nice calm area making for great fishing. Continue along the northwest shore for another 0.9 miles and reach a small stream coming down from the northwest which drains a small lake above and to the north. Descend 50 feet to the creek, cross to its east side, and follow this drainage up to a very broad 10,160 foot saddle. Descend a short ways to the upper lake outlet stream and find a place to cross it. Wading may be required in early season. Reach the Upper lake at 10,170 feet and hike east around its south shore, then north around the east shore for 1.3 miles from the outlet. Stay close to the shore on the east side to avoid annoying talus traversing. Begin an ascending traverse and cross a small stream reaching a small tarn at 10,330 feet (200 feet above Upper Aero Lake). The camping at this tarn is fantastic and out of the bugs that flock the lake shore below. Views of Glacier, Villard, the Spires and the upper lake below are out of this world! This beautiful spot is 3.3 miles from where the official trail ends making the total distance 8.7 miles from the trailhead with only a 1,500 foot net elevation gain.
SKY TOP CREEK APPROACH
From the Tri-Creek junction (see above), instead of taking the left trail for the Aero Lakes approach, continue straight and follow the trail as it heads along the right (south) side of Star Creek for a few minutes. Locate a place to cross Star Creek on logs or rocks and pick up the trail on the north side. Continue to follow the north side of Star Creek downstream in an eastward direction and descend on the trail about 100 feet to Sky Top Creek. This entire Tri-Creek Junction is confusing since many social trails criss-cross the large meadow where these three creeks converge. Best to avoid trying to find the correct route through here at night. Parties have gone in circles here for hours in the past.
The trail reaches the north/west side of Sky Top Creek and continues near its shore for 0.75 mile to the stream draining Aero Lakes. Cross this barrage of streams and marshland on mainly well placed logs (or wade in early season) and locate the trail on the other side. Continue another 0.75 mile to a large flat meadow at 9,400 feet. The trail follows the left side of this half-mile long meadow. Just before the large cascade at the head of the meadow, the trail heads up to the left, over a small ridge and begins climbing steeply for another mile to Lone Elk Lake at 10,065 feet. Shortly before reaching the lake, the trail crosses a small stream draining Shelter Lake off to the north and passes over a small saddle to bypass the waterfall a few feet below the lake. The first real good views of the Villard Spires can fe found at Lone Elk Lake.
Hike around the left (west) side of the lake and cross the inlet stream above the small cascade. Continue around the right (east) side of Rough Lake which sits at 10,140 feet and hike up the right side of its inlet stream through a narrow gorge. Cross to the north side of this stream when possible (jump across a narrow section) and hike up the hill and reach the top of a broad ridge at 10,450 feet to the left (west) and roughly 100 feet above Lower Sky Top Lakes. Hike around the left side of the Lower Lakes and descend to the west shore of the two-part upper lake. Continue along the west shore of the upper lake (which is divided into two sections by a short stream) and set camp on a small flat patch of grass at the north end of Upper Sky Top Lake just below the 10,840 foot saddle between Point 11,379 and the Villard Spires. Camp is at an elevation of 10,480 feet. This approach is 9 miles each way from the trailhead with a net elevation gain of just over 1,600 feet.
Starting From the Sky Top Lakes valley southwest of Granite Peak, aim for the lower right corner of a massive slab on the southwest face. Scramble up the talus in a northward direction, passing by a beautiful green tarn and continue off to the right to the base of the slab. Make sure you stay right, close to the low saddle between Cairn Mountain and Granite Peak, as the cliffs further left can be 4th class to ascend. There is typically a snowfield you have to ascend or cross as you cut back left to the base of the slab. Unless it's a very dry year expect snow here where crampons and an ice axe are required. Traverse to the left along the base of the slab until you reach to left edge. Here you have two options for the route, Couloir 1 or 2, and they have been confused in the past. Note that some people call the shorter Couloir 1 route I describe below as the SW Ramp, such as Steve's route description linked at the bottom of this page. Most people probably don't even know there is a second couloir and do couloir 1. Don't fret over the fact there are two options though, as I am going to recommend you do Couloir 1 described first below. It's just simpler overall, shorter, and much safer. The photo below is taken from Steve's description and shows the two options. He labels what I have dubbed Couloir 1 as the SW Ramp route. When I descended the mountain after doing the Granite Peaks Traverse, I went down this route, and from my studies, most people do this route anyway.
From the left edge of the large slab, immediately turn right and enter the small gully (which is known as the ramp) and ascend up the top of the large slab initially, then continue up the gully. This small gully has a bunch of steep rock, so be ultra careful not to rain boulders down on your fellow climbers below, and watch for people above you. Most of the gully is straight-forward, but the crux is a small steeper step which typically holds snow. People have been able to scramble around this snow step or if you have crampons you can put them on. Hand lines have been placed here as well. Past this crux, the gully will end with large blocks above you to the left, and you will reach the small ridge overlooking the gash. Scramble up to this ridge where the terrain abruptly ends and the gash becomes visible as a huge drop below! When you gain the ridge, follow it up and left on now fairly solid rock. This ridge takes you directly to the summit ridge where you can then walk a few yards to the right to the highest point. Cairns mark the route from the point where the gully (ramp) meets the gash to the summit.
I have not done this route but people do not recommend it. It apparently has even more loose rock and typically holds ice longer than option 1 above. From the left corner of the slab, instead of heading up the obvious gully, if you traverse right a few minutes and cross onto the darker colored rock, you will come across another, steeper gully that cannot be seen from anywhere really. Climbing this route may involve ice climbing...the end. If you do this route, it will dump you out on the summit ridge further west than the other route and you'll have to walk east on the summit ridge a little longer to reach the summit.