Hikers climb up to Halemau’u Trailhead. Backpackers hike through cooled lava. Haleakala Loop Details Backpack: Volcanic Haleakala National Park, Hawaii 3 days 20.6 miles 2,857 ft gain — 4,559 ft loss 6,266 ft min — 9,682 ft max Physical Challenge 3 of 10 Psychological Challenge 2 of 10 Beauty 7 of 10 Uniqueness 7 of 10