Koko Crater Botanical Garden is a 60-acre garden within Koko Crater, or Koko Head, at the eastern end of Oahu, Hawaii, where hot, dry volcanic conditions support a notable dryland collection. Established in 1958 and given the additional name Charles M. Wills Cactus Garden in 1966, it is part of the Honolulu Botanical Gardens system. Its plantings include plumeria, bougainvillea, kiawe, koa haole, adeniums, aloes, baobabs, cacti, euphorbias, palms, sansevierias, and a native grove of wiliwili trees. Organized by regions including Africa, the Americas, Hawaii, and Pacifica, the grounds also feature a two-mile loop trail and about 500 trees representing 200 species.