2 Best Sights in Honolulu and Pearl Harbor, Oahu

Some of the trees in this 14-acre botanical garden, which opened in 1931, date from 1853, when Queen Kalama allowed a young German doctor to lease a portion of her land. More than 170 years later, you can see these trees and many others along with bromeliads, orchids, and other tropical plants, some of which are rare or endangered. Look out in particular for the cannonball tree and the redwood-size quipo tree.

Tucked all the way back in Manoa Valley, this is a gem of an arboretum operated by the University of Hawaii. Reservations are required to visit its almost 200 acres, where you can hike to a waterfall or sit and enjoy beautiful views of the valley while having a picnic. You'll also see an ethnobotanical garden, a Hawaiian hale (house) and garden, and one of the largest palm collections anywhere—all within a parklike setting. The arboretum's educational mission means there are often regular talks and walks, plus classes on lei-making, lauhala weaving, Hawaiian medicinal arts, and more, which you can take for an additional fee.