This descent is very tough on the knees.
Most visitors plan to complete this challenging trail as a one-way excursion by arranging for a pickup at the end. Alternatively, leave a car at both ends and make it into a multi-day backpacking journey by utilizing the park's fine backcountry camping/cabins with the necessary permits. Most people spend the night at the Paliku cabin and start the descent to the southern coast early in the day to avoid the worst of the heat.
From the 3-way intersection with the Halemau'u Trail
and the Lau'ulu Trail, take the Kaupo Trail south across the flat crater floor before dropping off the lip and heading down the volcano's hillside through brushy, steep terrain. It was originally thought that this "gap" in the crater rim wall was blown out in a spectacular Mount St. Helen's-style eruption, but recent research has shown that it was formed instead by wind and rain erosion.
You'll almost certainly have all the solitude you seek on this remote, infrequently used trail. Enjoy watching for wildlife while crossing ancient lava flows, dry dense native vegetation and pristine forests. Be prepared for a tough, rocky path that can sometimes be hard to find. Intense switchbacks are interspersed with somewhat level sections and constant ocean/Big Island views in the distance.
Just as you leave behind the prominent ridgeline that has been looming above, the trail crosses a fenceline from National Park land into private property. Trail users have permission to continue through, but please be respectful. The remainder of the route is on old doubletrack through ranch land. The grade steepens considerably near the Kaupo Cutoff
and Kaupo Side Loop
. You may inadvertently take one of these options due to the increasingly vague trail markings here. Proceed through pastures looking for the NPS markers to stay on track. The trail ends upon reaching the more established-looking dirt road and trailhead, but it is another few miles on the Kaupo Gap Road to reach the Piilmani Highway 31.
Heed the warnings and be prepared for cold and unpredictable weather. Also, be aware that the high altitude will cause dehydration and fatigue much faster than at sea-level. As of this writing, no food is available for purchase inside the park, so bring your own.
Koa forest, Ohia trees, endangered birds.