Koko Crater Botanical Garden is located in a 60-acre basin inside the tallest tuff cone on the eastern end of the island of Oahu.  Garden plantings occupy the inner slopes and basin in the Koko Crater.  A two-mile loop trail begins with a 40 year old stand of plumerias, then leads through a variety of dry land plant collections from Hawaii and around the world.  The four main collections arranged by geographical areas are:  The Americas, Madagascar, Hawaii and Africa with additional collections including Cacti, Dry land Palms, Alluaudias, Aloes, Sansevierias, Euphorbias, Baobabs, and Adeniums.  Of special note is the native grove of wiliwili trees (Erythrina sandwicensis).