Pu’u O Umi is a natural area reserve that covers over 10,000 acres of the summit lands of the Kohala Mountains. The reserve hosts two rare kinds of montane bogs surrounded by ‘ohi‘a forests, along with shrublands. Hiking within the NAR often feels as if you are in the movie Jurassic Park, as the ferns and moss lend itself to a prehistoric ambiance. This area is one of the few legal access sites for the Kohala Mountains, and it is certainly the easiest access to the wet forest. However, once you make it to the reserve, there is no maintained trail, and you’ll be following trails established by hunters that have been blazed with plastic ties.
The hike up to the reserve can be worth the trip in and of itself. Park at the pullout for the Koai’a Tree Sanctuary instead of entering the fenced in sanctuary and follow the gravel road directly adjacent on the right. This 2-mile stretch is called the Koai’a Corridor and is a public road, so if you have four-wheel drive, you are welcome to enter through the gates. The land that the corridor neighbors is currently being restored through the Kohala Watershed Partnership, and there are numerous fence stiles you can climb to take a peek at the gulch. This is a really interesting corridor because the base only receives 30 inches of rainfall per year, while the top, where the corridor meets Pu’u O Umi Reserve, receives over 150 inches of rain per year. Thus you’ll see the vegetation start to slowly change as you move up the mountainside. To the right side of the corridor is pasture land, and because of the lack of vegetation, you get awesome views of Mauna Kea, Mauna Loa, Hualālai and the Kohala coast.
The boundary fence for the NAR is very prominent as you move from the barren pasture land to a virtual wall of ferns and trees. You’ll see a red gate, and that is your opportunity to cross into the wet forest. Once in the forest, be prepared to get muddy and wet as you pick your way through the dense vegetation. While it might be sunny where you parked your car, there is a daily mist that rolls onto the mountain tops, keeping you cool and damp, and also making it hard to find your way at times. Look for the plastic tags left by hunters for the easiest routes through the NAR or to the top of Pu’u O Umi, at 5,260 feet, if that is your ultimate goal. Don’t expect a view here, as the pu’u is covered with ʻōhiʻa trees and the mist is generally obstructive. Just the sheer experience of walking through this lush and wild reserve leaves hikers feeling satisfied. Take time to poke around some of the gulches within the reserve, too. These are narrow and steep at times, but the waterfalls and pools are pristine. You probably won’t see another soul on this hike, but you might want to wear bright colors just in case there are hunters on the prowl for wild (and incredibly destructive) pigs.
The Kohala Watershed Partnership has bimonthly volunteer opportunities within these mountains, and these service trips can be another great way to experience different locations within the NAR. Check out their website for details about these volunteer outings.