Denali National Park and Preserve
Denali, in Alaska's interior, encompasses more than 6 million acres of land and is home to North America's tallest peak at 20,320 feet -- Mount McKinley. Black bears and grizzly bears are among the stars for wildlife spotters (just keep your distance).
This national park is about the size of Vermont, yet only a handful of trails exist in this vast, solitary area. Most of the trails are within three miles of the park entrance, but if you're adventurous, you can explore the wild terrain, which ranges from a low-elevation taiga forest to snow-covered mountains. You'll need to get a backcountry permit in person before you set out.
Three park-authorized companies offer guided backpacking: Alaska Mountaineering School, Mountain Trip and Rigging for Rescue.
North Cascades National Park
Escape to this national park in Washington state and surround yourself with mountains, glaciers and streams. Grizzly bears are among the 75 mammal species that inhabit the wilderness.
Backpacking is popular at North Cascades and trips can range from an overnight on relatively level land to multiday hikes over multiple mountain passes. Mountaineering treks for varying skill levels are an option, too, but this is not a beginner's venture.
Beaver Loop trail is a moderate, forested route. The 34.2 mile journey offers a side trip with views of Challenger glacier and peak and usually takes three to four days.
The park service lists authorized guides for North Cascades backpacking on its site.