All hail the granddaddy of national parks. Established in 1872, Yellowstone is the oldest and most iconic protected wilderness in the world. Most visitors gape at its big-screen natural drama from their cars–and there’s a lot to see, what with all the wolves and grizzlies, burping geysers, and steamy, pristine rivers filled with monster trout. But if the show’s this good from the road, wait until you see what’s hiding over the next ridge. When you probe Yellowstone’s backcountry, you immerse yourself in a 2.2-million-acre playground that includes remote 11,000-foot peaks, meadows saturated in wildflowers, and a trail network that dates back to the Indian wars.