The only way to access this 30-mile stretch of wild glacier-green waters is by bush plane or horse. It's worth the effort. Early-season trips mean riding booming Class IIIs and Vs through limestone gorges; late spring and summer bring spectacular fly-fishingcutthroat trout grow as long as 22 inches. Chances of seeing other people? Low. Chances of seeing a grizzly? High. The Glacier Raft Company will fly or horsepack small groups in for multi-day rafting or guided fishing trips (glacierraftco.com).
St. John River, ME
The St. John, wilder and less accessible than its better-known cousin, the Allagash, is navigable only during the May melts. Drive the four hours from Bangor to Baker Lake and launch your canoe down the 100-mile ribbon of glossy straightaways and mellow Class IIs. The river cuts through the deep northern woods near the Canadian frontier, where the only traces of civilization are a few ghost logging camps. Easy paddling days mean pulling into camp early for afternoons of catching brook trout. Canoe Maine does a six-day trip ($750 per person; canoemaine.com).
Boundary Waters Canoe Area Wilderness, MN
Start with the aurora borealis flittering in a moonless sky. Add in a wolf's howl, 1,000 frozen lakes, and a sauna and you've got the Boundary Waters in winter. You can't always count on the northern lights or the wild canids, but you can depend on Gunflint Lodge and Northwoods Outfitters (gunflint.com) for everything else. Rent a pair of snowshoes and explore the five miles of trails outside your door. An ideal watching/listening spot: High Cliffs, a rise overlooking two lakes. Your sauna-equipped cabin welcomes you home (from $199).
Upper Selway River, ID
More than 1,700 people vie for 62 private launch permits to run the Upper Selway in the yearly U.S. Forest Service lottery. The prize? The chance to have one of the most spectacular rivers in America almost all to yourself. Paddle 47 miles of snowmelt-engorged Class III and IV rapids cutting through the 1.3-millionacre Selway-Bitterroot Wilderness, along the Idaho-Montana state line, passing steep granite hillsides thick with cedar and fir trees. Go for whitewater in early summer, hungry cutthroat trout in July. Bypass the lottery by reserving a year in advance with an outfitter like Three Rivers Rafting (five-day trip, $1,800 per person; idaho3rivers.com).
Turkey Creek Hot Springs, NM
Reaching these pools, deep in New Mexico's Gila Wilderness, 300 miles south of Albuquerque, isn't easy. It's a four-mile hike from the end of Turkey Creek Road, outside of Gila, and you cross the creek half a dozen times. The payoff? A six-foot-deep rock Jacuzzi in one of the most remote wilderness areas in the country. Cool river water mixes with 165-degree spring outflows, then pours into a stone tub constructed by a few ambitious soakers. Leave your swimsuit at home.