Akaka Falls is the Big Island's most impressive easily-reached waterfall — a single 135-metre plume dropping into a fern-lined gorge, twenty minutes' drive north of Hilo past the old plantation town of Honomu. A paved 0.6-kilometre loop trail winds through dense rainforest of bamboo, wild orchids, and draping philodendrons, passing the smaller Kahuna Falls before arriving at the main viewpoint. The walk takes half an hour at a stroll and requires no fitness at all, which makes the scale of the falls at the end feel like a cheat.
Go in the morning, when the light hits the gorge and before the tour buses arrive from the Kona side. It rains here even more than in Hilo, so the falls are reliably full year-round; bring a rain shell rather than waiting for a dry day that may never come. There is a modest state park entrance and parking fee. Combine the trip with a stop in Honomu, whose short wooden main street has held onto its plantation-era character, and with the scenic four-mile drive along the old Mamalahoa Highway at Onomea Bay on the way back.