The way From the north, take US 191 and US 20 132 miles from Bozeman, MT. From the south, link US 191 and US 87 for an 82.7-mile drive from Jackson, WY. Access the west entrances from West Yellowstone, WY; and the east from Cody, WY.
Books/maps Select Peaks of Greater Yellowstone, by Tom Turiano ($45, indomitusbooks.com) and Hiking: Yellowstone National Park, by Bill Schneider ($17, falcon.com). USGS quads: Lake Butte, Frank Island, Sylvan Lake, Trail Lake, Plenty Coups, and Eagle Peak ($8 each, store.usgs.gov)
Season You can easily do this hike between July and early September, but the last half of July and first half of August are your best bet for windows of reliable weather and blooming flowers.
Permits Required (free, $20 if reserved more than 48 hours in advance). Note: Getting approval for at-large camping in a spot this remote involves convincing skeptical rangers that you have what it takes to venture off the beaten track. Turiano recommends coming prepared with an annotated map and a trip resumé to establish your creds. He says, “If you can show the experience level to match the route—and this is not a beginner traverse—rangers will usually say, ‘OK, just follow LNT ethics and bear protocols,’ and send you on your way.”
Contact (307) 344-7381, nps.gov/yell
Trip data Download this route at backpacker.com/hikes/mysterymountains.