- From the trailhead, the Ainapo Trail ascends 7,600` in 10.2 miles to the National Park Service cabin on the rim of Mokuaweoweo crater at the summit of Mauna Loa. Vegetation varies from mixed mesic Koa/Ohia forest to alpine stone desert. Ahu, stone cairn trail markers, identify the route over pahoehoe lava sections. The beaten trail over a`a lava may be totally obscured by snowfall. Rain catchment water is available at the trail shelter at Halewai at the 7,750` elevation.