You are here

The historic Ainapo Trail leads to the summit of Mauna Loa volcano on the Big Island. For many years the trail was the primary route leading to the top of the formidable mountain which is considered to be the most massive mountain on Earth by volume.

The original Ainapo Trail begins on the southeast flank of Mauna Loa at about 2,000 feet (610 m) above sea level. As it winds its way up the volcano the trail continues for 35 miles (55 km) to the 13,200 feet (4,000 m) elevation at Mauna Loa’s summit crater called Mokuaweoweo.

Today only the upper part of the trail above 11,650 feet (3,550 m) remains in its original condition and leads 11 miles (18 km) to the summit crater. The lower parts of the trail cross private farms and ranch lands.

A trailhead along Ainapo Road (north of Hawaii Belt Road) leads through the Kapapala Forest Reserve to the historic section of the Ainapo Trail leading to the summit crater. The trailhead is located in Kau on the mauka (mountain) side of Hwy. 11 near the 40.5 mile mark.

This section of the Ainapo Trail climbs 7,600 feet in elevation from the trailhead along a 10.2 mile route that ends at the rim of Mokuaweoweo Crater. At the end of the trail is a Mauna Loa Summit Cabin managed by the National Park Service.

The terrain along the Ainapo Trail varies from native ohia and koa forests to alpine desert. Rock cairns mark the trail’s route over the sections that are largely barren lava. During winter months large areas of the trail may be obscured by snowfall.

The Ainapo Trail was formerly known as the Menzies Trail after explorer Archibald Menzies who became the first Westerner to climb Mauna Loa when he made the ascent in 1794. A naturalist on the Vancouver expedition, Menzies was assisted by about 100 porters and used a barometer to measure the volcano’s summit elevation.

Along the historic trail were various temporary rest areas that included everything from rock shelters to lava tubes. At the upper elevations where the trail traverses the barren lava rock many rock cairns marked the route. In the late 1800s and early 1900s the trail was widened for the mules and horses that began bringing visitors to the top of Mauna Loa.

After a new trail was built by the U.S. Army in 1915 leading from the crater atop Kilauea volcano to the top of Mauna Loa, the Ainapo Trail was largely abandoned. While some parts of the lower trail may be accessed through private tours, only the upper Ainapo Trail is open to the public.

Only experienced hikers who take all proper precautions should attempt to reach the summit of Mauna Loa. Weather at the upper elevations is extremely unpredictable, and is often freezing cold with strong winds.

To reach the Ainapo Trail follow Hwy. 11 in Kau to the cattle guard near the 40.5 Mile Marker. The trail is open during daylight hours. Contact the Hawaii District Division of Forest and Wildlife for reservations and for permits to camp at the trail shelter. The Ainapo Trail was placed on the National Historic Register in 1974 and is designated as a State Historic Site.