Pu'u O'oNāpau Trail

Hawai'i Volcanoes National Park

Round Trip Mileage: 11.8 miles (can be split up with a backpack)

Elevation Gain: 860’

Gear: This is a long hike in a vast wilderness, so pack enough gear for a very long day hike. Bring extra water and food, and ensure you have appropriate raingear and some warm clothing because this entire hike is about 3000' above sea level. Consider carrying a painter’s mask because you can be downwind of the dangerous sulphur dioxide gases issuing from Pu’u ʻŌʻō at times.

Weather: NOAA forecast for Nāpau Trail

Learn about Hazards

Read my Disclaimer

Learn about Leave No Trace Principles

Area Closures: The Nāpau Trail, the Nā'ulu Trail, and Nāpau Campground can be closed at times due to dangerous eruption conditions. Check current Area Closures and Advisories.

Gas Levels: This hike takes you close to the current eruption site, Pu’u ʻŌʻō, where tons of dangerous sulphur dioxide gases issue each day. Check current conditions with the Hawai'i SO2 Network.

Map: Topographical Map of Nāpau Trail


Overview: This long dayhike or backpack is one of the best in the entire National Park, and is currently the closest you can get to the site of the eruption, Pu’u ʻŌʻō. This hike starts with the beginning of the Pu’u Huluhulu trail. Pu’u Huluhulu, literally hairy hill, is a nice diversion and provides a decent view of Pu’u ʻŌʻō, especially with binoculars or telephoto lenses. The Nāpau trail crosses vast oceans of new lava and skirts a few massive craters before entering a 150 year-old rainforest. After hiking in the rainforest for a bit, you abruptly come to the edge of Nāpau Crater, which provides the closest vantage possible to the current eruption site inside the National Park. If you’re lucky enough (or plan well enough) to do this hike on a clear day, you’ll have an amazing view. It used to be possible hike closer to Pu’u ʻŌʻō, but the current eruption cycle has made traveling past the Nāpau lookout unsafe due to dangerous gases and ground conditions. This is unlikely to change in the near future. Those wishing to make a backpack out of this long hike can camp at the Nāpau Campground located at the end of the trail. Register for a camping permit and pay your fee at the Visitor Center or the Backcountry Office. Even if you're not camping, everyone traveling on the trail past Pu'u Huluhulu (on either the Nāpau Trail or the Nā'ulu Trail) must register for a free permit at the trailhead kiosks. Sign out at the end of your hike so the Rangers know you're off the trails. 

 Hiking the Napau Trail


Getting to the Trailhead: From the Park entrance, drive about 50 feet and turn south on Crater Rim Drive. Follow Crater Rim Drive to Chain of the Craters Road. On the Chain of the Craters road, find the Mauna Ulu parking area at the end of a short spur road that departs Chain of the Craters road between the 3 and 4 mile markers. The spur road dead-ends into a roundabout with a small parking area with a restroom. 

 Steam Vents along the Trail


The Hike: From the parking area, walk about 100 feet on pavement and turn left on the Pu’u Huluhulu trail. At this trail intersection, find a Park Service kiosk where you will need to register for a free permit. Also sign out at the end of the day so the Rangers know you are off the trail. This portion of the trail is marked with numbered sites where you can learn about lava flows and the flora and fauna along the trail. You can find a trail guide near the trailhead for a few dollars donation or download it: Mauna Ulu Eruption Guide. Walk for 1.2 miles, following cairns, along pāhoehoe until you reach the trail intersection of the Nāpau Trail and the trail that leads to the summit of Pu’u Huluhulu. This is as far as you can go without a permit. Pass Pu’u Huluhulu and enter the permitted area and a vast expanse of lava. The shield volcano to the south is Mauna Ulu, which erupted until 1974. Follow the changing path through this area set by cairns. Pulu FactoryAfter a stunning 2.2 miles of hiking across this wasteland, you’ll come to the edge of Makaopuhi Crater. This crater erupted in 1922, 1965, and 1972, and the 500 year old double crater is the largest in the east rift zone. The trail here begins to skirt the crater and enters a dense and beautiful rainforest. Although this area seems like old growth, this area was covered by lava in 1840. Pass through the sometimes dense rainforest toward an old Pulu factory. Pulu is the felt-like substance in the trunks of the Hāpuʻu pulu ferns endemic to the island, and it has natural antibiotic properties. This factory processed pulu from 1851 – 1884, when the industry failed because pulu broke down into dust very rapidly in drier climates. From the first time you intersect Makaopuhi Crater, it’s another 2.5 miles to the edge of Nāpau Crater. The trail can be quite overgrown in the rainforest sections, but the right way to go is always obvious. At the end of the trail, you’ll abruptly find a steep overlook in the rainforest over Nāpau Crater onto Puʻu ʻŌʻō. It has erupted constantly since 1983. Be careful along the edge, and go no further. Return the way you came.

Makaopuhi Crater along the Napau Trail 

Alternative Option: The Nā'ulu Trail is a shorter alternative to the Nāpau Trail, but is more likely to expose you to dangerous gas from Pu’u ʻŌʻō. It is often closed, and also requires a permit. I recommend the Nāpau Trail for these reasons. If you want to hike this way, find the Kealakomo parking area between the 9 and 10 mile markers along the Chain of the Craters road. It is easy to miss. The trail begins on the north side of the road, where it’s 3.3 miles and over 500 vertical feet to the intersection with the Nāpau Trail on the south side of Makaopuhi Crater. Going to the Nāpau overlook is 10.5 miles round-trip.