A hike in Hawaii Volcanoes National Park’s lesser-visited Kahuku Unit

Though Hawaii Volcanoes National Park (HVNP) is one of the state’s largest draws, few visit or even know about its Kahuku Unit on the southerly slopes of Mauna Loa. Thirty miles southwest of the park’s main entrance, the 116,000-acre former ranch plot was acquired by the park in 2003. It’s only open to the public on weekends, but when it is, the park’s five trails are ripe for exploration and staff often lead guided hikes on the shorter ones. Along them, you’ll find three distinct lava flows from eruptions in the mid-19th and early 20th century, ohia forests, cinder cone, a pit crater, lava trees, grassy ranchlands and scenic ocean vistas.

Last week, I joined several dozen visitors and residents on a 2-mile jaunt to the forested pit crater within the Kahuku Unit. The hike was part of an ongoing series of hikes and informational discussions led by park officials in honor of HVNP’s 100th birthday.

Our introduction to the shifting landscape’s history began with the squirt of an alcohol bottle and a stiff-bristle brush on the bottom of our shoes. The grassy pastureland that stretched in front of us had changed numerous times over the past two decades and the park was trying to prevent yet another: the spread of rapid ohia death, a fungus dangerous to the endemic tree.

Our guides, David Benitez, a park ecologist and Jonathan Faford, a wildlife biologist in the unit, shared that this expanse was a former sandalwood and koa forest that had been cleared in the 1930s and again between the 1950s and ’60s to make way for cattle pastures and its use as a trophy-hunting concession. Faford has spent his time in the unit hunting down the area’s remaining ungulates—some bison and many mouflon, a type of wild sheep. His team has whittled mouflon numbers from 2,000 to the handful that still roam the space today. The eradication of these and other ungulates are done without baits or toxins and are necessary, he said, to restore the land to its original forested nature. “Think of koa as ice cream cones and ungulates as packs of small kids,” added Benitez.

Evidence of the mouflon’s removal is everywhere along the hilly trail—springing up amid the grass were waist-high koa seedlings. Some of the tiny saplings sported the usual sickle-shaped leaves on top and more fern-like fronds toward the bottom—its two types of leaves are one of the many unique and mysterious features of koa. The koa here once grew so tall that Kamehameha harvested trees to build his own outrigger canoes from a plot nearby. The seedlings I spotted may very well be the ancestors of those same trees.

Another interesting feature of the higher elevations beyond the trail in this section of the park? It’s one of the few places in the world remote enough—and with so few human visitors— that ants have never been introduced.

A few more curvy turns and we arrive at the tour’s highlight: A collapsed pit crater. With sheer walls plunging some 230 feet, the depression is a reservoir of native rainforest and affords a glimpse of how the area must have once looked before its more modern changes. “No [big] animals could get down there and survive—it would have been a one-way ticket,” said Benitez. Yet, not for Benitez himself. He was one of a small team to rappel down the crater walls in 2005 for a botanical study. Inside the isolated environment, they found ohia and koa growing taller than elsewhere on the property, and below them, native shrubs, grasses, the endangered violet haha and ten species found nowhere else in Kahuku. These finds will inform park decisions as they manage it toward a more natural state.

On the final stretch back to our cars waiting at the end of the trail, the group stopped to look out over a particularly scenic stretch of pastureland some 2,000 feet above sea level. In the distance, windmills near South Point whirred capturing seaside breezes. “This is a view that, hopefully, won’t be here forever,” said Faford. We tried to imagine the scene: a thick understory of native ferns and native trees casting their shade—their trunks and foliage shielding glimpses of the sea. I, for one, wouldn’t mind a bit.

All tours meet near the main parking area and the park recommends bringing sturdy footwear, water, raingear, sun protection and a snack. All hikes start at 9:30 a.m. For further details and current hikes offered, visit Hawaii Volcanoes National Park’s Kahuku Hikes page.

Hawaii Volcanoes National Park Kahuku UnitThe Kahuku Unit is located on Kahuku Road off Highway 11 between mile markers 70 and 71 and between Ocean View and Waiohinu in Kau. The unit is open weekends only from 9 a.m. to 3 p.m. The 3-mile, moderate Glover Trail featured in this post is always accessible for self-guided walks during the unit’s open hours and has informational booklets available at its trailhead for a $2 donation.