Mauna Loa Trail in Volcanoes National Park

Probably the most challenging hike in Hawaii, this 7 1/2-mile trail goes from the lookout to a cabin at the Red Hill at 10,035 feet, then 11.6 more miles up to the primitive Mauna Loa summit cabin at 13,250 feet, where the climate is called sub-arctic, whiteouts are common, and overnight temperatures are below freezing year-round; there's often snow in July. This 4-day round-trip requires advance planning, great physical condition, and registration at the visitors center. Call tel. 808/985-6000 for maps and details. The trailhead begins where Mauna Loa Road ends, 13 1/2 miles north of Highway 11.