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.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.