I took this out-and-back hike in August 2022. It was a 9.3 mile hike one way. You start in relatively populated national forest land and then as you rise through the mountains, reach the Wilderness area. The trail climbs through Bear Basin, switch backing up the bowl of the basin to the first pass, which is stunning. The descent down the pass is rough with lots of steep gravel. The trail splits and you take the high trail to the east, over the next pass to Summit Lake, which is nestled between two mountains, then over the lass tiny pass and down into the last, big basin. Hike along the meadow until you reach Thompson Lake at the foot of Gallatin peak. You can summit the peak, but I didn't. I surely didn't see a reasonable trail up it!
Looking into Bear Basin
Wildflowers
Looking down into Bear Basin from the pass
Summit Lake
Towards Thompson Lake
Thompson Lake
Sunrise at Thompson Lake