Laura and I visited the Hawaii Tropical Botanical Garden outside Hilo on our drive from Volcano to Hamakua. It far exceeded our expectations and I’d highly recommend an hour or so stop if you’re on the Big Island.
The garden is along a trail that’s roughly a mile loop. It’s located off a scenic road which was among the best drives we did on the island. Just a mile south of it is the Onomea Bay Trail, which we walked as well. The trail actually passes through part of the garden, but you can’t get into the main area without first buying tickets at the main entrance.