1. Tongass National Forest, AK
This Alaskan wilderness is filled with huge Sitka spruce, western hemlock and cedar trees, some up to 800 years old. But that's not all. There are also majestic glaciers and ice fields within the national forest. At 16.7 million acres, Tongass National Forest is the nation's largest national forest. Incidentally, Alaska also has the most forests, with a wonderful 21.9 million acres. Over one-third of Tongass National Forest is designated as federal wilderness, protecting natural habitats for brown and black bears, mountain goats, black-tailed deer, wolverines, river otters, harbor seals and bald eagles (to name a few).