Mauna Loa Observatory Trail
Mauna Loa Observatory Trail information
The easiest way to summit Mauna Loa ('Long Mountain') is via this trail. Drive up to the Mauna Loa Observatory at 11,150ft, then pick up the 6.4-mile walking trail for the remaining 2500ft to the top. It's a steep, exhausting, all-day adventure, but also an exceptional one that allows experienced hikers to conquer a 13,000ft mountain in one day. There are no visitor facilities or bathrooms at the observatory.
Begin hiking by 8am; you want to be off the mountain or descending if afternoon clouds roll in. The trail is marked by ahu (cairns), which disappear in the fog. If fog does roll in, stop hiking; find shelter in one of several small tubes and hollows along the route until you can see again, even if this means waiting till morning.
It is nearly 4 miles to the trail junction with the Mauna Loa Trail (an alternative multiday backpacking route to the summit). Allow three hours for this gradual ascent of nearly 2000ft. If it weren’t for the altitude, this would be a breeze. Proceed slowly but steadily, keeping breaks short. If you feel the onset of altitude sickness, descend. About two hours along, you re-enter the national park, and the old lava flows appear in a rainbow of sapphire, turquoise, silver, ochre, orange, gold and magenta.
Once at the trail junction, the majesty of the summit’s Mokuʻaweoweo Caldera overwhelms you. Day hikers have two choices: proceed another 2.6 miles and three hours along the Summit Trail to the tippy-top at 13,677ft (visible in the distance), or explore the caldera by following the 2.1-mile Mauna Loa Cabin Trail . If you can stand not summiting, the second option is extremely interesting, leading to even grander caldera views and a vertiginous peek into the awesome depths of Lua Poholo – a craterlike hole in the landscape.
Descending takes half as long as ascending; depending on how far you go, prepare for a seven- to 10-hour round-trip hike. Bring copious amounts of water, food, a flashlight and rain gear, and wear boots, a winter coat and a cap – it’s cold and windy year-round.
Day hikers do not need a permit, but if you would like to overnight at Mauna Loa Cabin, register the day before at Hawaiʻi Volcanoes National Park's Backcountry Office , where rangers can inform you about current trail conditions and water-catchment levels at the cabin.