North of Hilo on the Big Island’s lush Hamakua Coast, a scenic drive splits from Route 19 to link Papaikou and Pepeekeo. This is the old Hawaii Belt Road, aka the Old Mamalahoa Highway. Two short public shoreline access paths, the Onomea and Donkey trails, head from this scenic drive in the vicinity of the Hawaii Tropical Botanical Garden. They offer immersion in gorgeous tropical jungle and views out over straight-out-of-paradise coves forming little embayments along the larger, stunning Onomea Bay.
This modest Onomea Trail System is part of the State of Hawaii’s Na Ala Hele network. Given these paths border and pass through the grounds of the Hawaii Tropical Botanical Garden, it’s imperative to stay on the signed Na Ala Hele public-access route—otherwise, you’ll be trespassing. Sturdy footwear (hiking sandals or shoes) is recommended given the moderate grade and rocky bits, and you’ll want raingear on hand just in case.
Two trailheads along the Old Mamalahoa Highway serve the Onomea Trail System. The northern trailhead marks the Donkey Trail, so-called because it was once a cart track used to transport goods—by, yes, donkey—to and from the Onomea Bay shipping port. It lies just north of the Hawaii Tropical Botanical Garden parking area. The southern trailhead is for the Onomea Trail proper. You’ll find it about at the halfway point of the scenic drive, two miles from either the Papaikou or Pepeekeo end.
Both of these trailheads are marked with brown Na Ala Hele signs labeled “Onomea Trails.” The dirt lots serving the trailheads are quite small, with room for only a handful of cars.
The half-mile-long Onomea Trail leads on an old paved path down from the southern trailhead. The generous trade-wind rainfall of the Hamakua Coast is apparent in the luxuriant vegetation, which provides a wonderful jungly ambiance.
Where the path hits the Alakahi Stream, a righthand branch—labeled on the trailhead map as the “Alakahi Trail”—leads a short distance down to the lovely Kukilu Bay. Gnarled shorefront trees, lava-rock outcrops, crashing surf: It’s a rather mesmerizing pocket cove. Don’t expect much in the way of sand, but the gorgeous scenery more than compensates.
Kukilu Bay isn’t a good place to swim, what with its often-heavy surf and roiling currents. Plus, you won’t find any lifeguards here.
There are only about 140 feet of elevation gain on the Onomea Trail. The climb back to the trailhead is semi-steep but quite manageable. Bear in mind its short unpaved section can be slippery in wet weather.
Many hikers combine the Onomea and Donkey trails. Back at the Alakahi Stream, where the “Alakahi Trail” heads east to Kukilu Bay, another fork continues across the stream into the Hawaii Tropical Botanical Garden grounds. This links to the Donkey Trail, which runs between the northern highway trailhead and a narrow point lying between Kahali and Kenenue bays. The stream crossing is generally no trouble, but, as anywhere in Hawaii, assess the water level before fording and don’t cross if the current’s strong and flood-muddied.
Given the generally light traffic on the Old Mamalahoa Highway, you can pretty easily make a loop of the Onomea Trail System by walking the roadside between the two trailheads. (They’re only about a half-mile apart.) Give yourself an hour or two for this jaunt, mostly to allow for a leisurely pace and plenty of drinking-up of the scenery and tropical vibes.
There tends to be a rather (ahem) healthy stock of mosquitoes along the Onomea Trail System, so repellent’s highly recommended.