The Na Pali Coast on Kauai is almost as paradisiacal as island backpacking gets. Walk 11 miles (one way) through lush bamboo, mango, and guava forests, past 100-foot waterfalls and sheer green cliffs, until you finally squish your toes in miles of sandy beach. The swimming is great for the ocean-savvy. Expect occasionally steep and rocky hiking, and some company from boat-in campers.
Contact: Na Pali Coast State Park, (808) 274-3445; www.state.hi.us/dlnr/
Sliding Sands and Kaupo Trails
Road's end (and trail's start) on the 10,023-foot summit of Haleakala is dry, rocky, and barren, but the contiguous trails' terminus at Kaupo Village is rainforest-wet at sea level, with all manner of topography and foliage in between. Expect sun and rain on this 18-mile hike on the island of Maui.
Contact: Haleakala National Park, (808) 572-4400; www.nps.gov/hale.
Mauna Loa Trail
In 36 miles (round-trip), this strenuous trail slowly climbs 7,000 feet to Mauna Loa's 13,677-foot summit, then quickly loses it all. Along the way, you'll travel from tropical rainforest to a summit so high it's sometimes snowcapped. Splatter cones and old lava flows add geologic color to the vegetable greens.
Contact: Hawaii Volcanoes National Park, (808) 985-6000; www.nps.gov/havo.