Koko Crater Botanical Garden
If you've visited any of Oahu's other botanical gardens, this one will be in stark contrast. Inside the tallest tuff cone on Oahu, in one of the hottest and driest areas on the island, Koko Crater Botanical Garden allows visitors the opportunity to see dryland species of plants including baobab trees, cacti, plumeria, and bougainvillea. www1.honolulu.gov/parks/hbg/kcbg.htm. COST: Free. OPEN: Daily sunrise--sunset.