Edging Kilauea’s Southwest Rift Zone, between the summit caldera and the Hilina Pali escarpment, the Kau Desert creates bleak, moonscape-esque scenery. As far away visually from the lush rainforest visible in other parts of Hawaii Volcanoes National Park, this volcanic waste nonetheless has its own transfixing charm. It’s a surreal place to hike and includes some of the most tantalizing archaeological sights on the Big Island.
The Kau Desert is not a true, or climatic, desert. In other words, it hasn’t formed primarily because of low rainfall: Annual precipitation here generally exceeds 39 inches. It is true that the Desert lies on the leeward flank of the Big Island, and thus exhibits a rainshadow climate drier than the northeastern side. But the primary cause of the Kau Desert’s sparse vegetation is geologic.
The Desert is underlain by porous lava flows and volcanic ash, and rainwater tends to percolate quickly deep into the ground. On top of that, acid rain is common here due to chemical reactions between atmospheric water vapor and volcanic gasses emitted from Kilauea Volcano. It all translates to a rather harsh environment for plant life: dry and even outright toxic. That said, you’ll see some vegetation in the Kau Desert, including widely scattered trees and shrubs.
Much of the Kau Desert is blanketed in a geologic formation called the Keanakakoi Ash, reckoned to have been deposited between the late 15th and late 18th centuries. This ash tells the story of explosive eruptions from Kilauea Volcano, likely when magma erupted into a lake within the summit’s Halemaumau Crater and flashed water to steam. The most famous such eruption was that of 1790, which overtook warriors under Chief Keoua, then battled his cousin Kamehameha. One of Keoua’s parties perished in the suffocating ash and hot gasses. This event—called Keonehelelei, “the Falling Sands”—was recorded by the tax assessor Frederick S. Lyman in 1857 based on information from Native Hawaiians.
Decades later, in 1919, geologists investigating the Kilauea eruption that produced the hill called Maunaiki chanced upon footprints preserved in the ash of the Kau Desert. At that time, this “Footprints Area” lay outside Hawaii Volcanoes National Park (which had been created only a few years before). In 1938, though, this archaeological area was added to the park.
Long associated with Keoua’s warriors, the footprints left in the Kau Desert ash are now thought to represent a range of people across a broader span of time. They likely mainly show the travels of Native Hawaiians along traditional Kau travel routes, memorialized whenever they passed through fresh ashfall.
A 0.8-mile trail from the Kau Desert Trailhead on Highway 11 leads to a shelter and exhibit in the Footprints Area. You’ll be able to see some of the ash-preserved footprints here: a remarkable testament to how long Native Hawaiians have occupied this place, and how intimately familiar they were with volcanic drama.
The Kau Desert Trail to the Footprints shelter (sometimes called the Footprints Trail) isn’t the only hike you can take in this striking place. About a mile beyond the shelter, you can follow the trail to Maunaiki. Here the Kau Desert Trail intersects the 6.3-mile-long Maunaiki Trail coming from a trailhead on Hilina Pali Road. That’s a rougher, harsher trek, much of it over raw lava rock.
From that Maunaiki junction, meanwhile, the Kau Desert Trail proceeds west, then south. A long hike brings you to the Pepeiao Cabin in the backcountry. Here the Kau Desert Trail continues east to the Hilina Pali Overlook at the end of Hilina Pali Road. The Kaaha Trail, meanwhile, drops down from Pepeiao Cabin to the wilderness coast of Hawaii Volcanoes National Park.
Whether you tackle a long day hike or backcountry adventure, or just check out the Footprints Area on a short walk from Highway 11, the Kau Desert is definitely worth experiencing firsthand. Just be sure not to forget your sun protection—and plenty of water!
-The 2018 Kilauea caldera collapse resulted in a lot of volcanic ash and dust being deposited in the Kau Desert. Ample quantities remain, and even light breezes can stir up this gritty debris. So it’s a good idea to wear sunglasses or other eye protection—even a bandanna or mask.
-Much of the Kau Desert portion of Hawaii Volcanoes National Park lies in its designated wilderness. Be prepared for remote conditions.
-Don’t stray off the trail in the Footprints Area. The footprints themselves and the ash deposits that contain them are fragile and easily disturbed.