Besides having the access road to Mauna Kea, the Saddle Road is a great place to explore by foot—especially on your way to Mauna Kea or on your way to/from the Hilo side and the Kona side.
Pu‘u O‘o Trail
Just after mile marker 24 on the way up from Hilo is the trailhead for Pu‘u O‘o Trail. From the small parking lot along the road, this trail heads to the south about four miles where it meets Powerline Road, a rough four-wheel-drive track, and returns to the Saddle Road. This area is good for bird-watching, and you might have a chance to see the rare ‘akiapola‘au or ‘apapane, and even wild turkeys. This area is frequently shrouded in clouds or fog, and it could rain on you. You may want to walk only partway in and return on the same trail, rather than making the circle.
Kipuka Pu‘u Huluhulu
A kipuka is an area that has been surrounded by a lava flow, but never inundated, that preserves an older and established ecosystem.Bird-watchers or nature enthusiasts should turn into the Kipuka Pu‘u Huluhulu parking lot across the road from the Mauna Kea Access Road turnoff. A kipuka is an area that has been surrounded by a lava flow, but never inundated, that preserves an older and established ecosystem. The most recent lava around Pu‘u Huluhulu is from 1935. At the parking lot you’ll find a hunters’ check-in station. From there, a hiking trail leads into this fenced, 38-acre nature preserve. One loop trail runs through the trees around the summit of the hill, and there is a trail that runs down the east side of the hill to a smaller loop and the two exits on Mauna Loa Observatory Road, on its eastern edge.
Pu‘u Huluhulu means Shaggy Hill, and this diminutive hill is covered in a wide variety of trees and bushes, which include mamane, naio, ‘iliahi (sandalwood), koa, and ‘ohi‘a. Some of the birds most often seen are the greenish-yellow ‘amakihi, the red ‘i‘iwi and ‘apapane, and the dull brown and smoky-gray ‘oma‘o. In addition, you may be lucky enough to spot a rare ‘io, Hawaiian hawk, or the more numerous pueo, a short-eared owl. The entire loop will take you 45 minutes or less, so even if you are not particularly drawn to the birds or the trees, this is a good place to get out of the car, stretch your legs, and get acclimatized to the elevation before you head up to Mauna Kea.
Excerpted from the First Edition of Moon Hawaiian Islands.