Say "Hawaii," and not many people think "cactus," but that's what you'll find at the Koko Crater Botanical Gardens in southeast oahu, an acre or two of the prickly stuff in fantastically weird forms that would impress Pixar animators: barrels and spires and twisting figures, some like a giant squid that took a nose dive into these arid soils. (Actually, the west side of all the islands is very arid, getting around 10 inches of rain yearly, and cacti grow also in the wilds.)
The 1,000-foot-high walls of the crater, which lies just inland from the crowded snorkeling site of Hanuma Bay, form a near circle around the 60-acre garden and create nifty acoustics for the zillion birds and dart about. And it's not all cactus. At the entrance (free admission) are another couple acres of bougainvilleas and plumera that combine for a perfumy explosion of color when they bloom in the spring. (Leis are made from plumera.) The homeward leg of the garden's two-mile loop trail is through a nation of palms, including Hawaii's only native, the loulu, and exotics from Madagascar and Africa—bushy, fernlike, fanned, and fronded—all clattering in the breeze that always seems to stir the crater's warm air. See page 92 of Oahu Trailblazer.
For the bird's eye view of the crater, and a cool-quirky hike, try the Koko Crater Stairs, the trailhead for which is across the highway from Hanauma Bay at Koko Crater Regional Park. You climb to the top (those 1,000 feet) on steps made of railroad ties that were part of a a World War II-era radar installation. Those with a fear of heights will get sweaty palms in one section, but it's not dangerous if you watch your step. See page 88 of Oahu Trailblazer.