Mauna Loa Cabin via Observatory Trail Backpack Professional Guide
Detailed Trail Description from our Guidebook
"For those in a hurry but still determined to see more of Mauna Loa than Trip 11 allows, the Observatory Trail offers a shorter route to Mauna Loa Cabin (but not to Red Hill Cabin) than the Mauna Loa Trail but with a greater risk of altitude sickness, especially if you stay overnight. That’s because you start higher and gain elevation faster.
Also see As a dayhike, below. Day 1 (Just under 6 miles): Take a moment to enjoy the view from the trailhead: Mauna Kea towers across the saddle, and huge, irregular patches of lava of different textures and tints plaster Mauna Loa’s slopes like pieces of a giant jigsaw puzzle. You’re hiking on an active volcano, so the following trail description could change. In that case, follow the Park Service’s cairns, not the description below."