The Tropical Botanical Garden west of central Sanya is a research-and-display garden specialising in the tropical flora of southern China and Southeast Asia. The grounds are extensive — figure on three to four hours if you want to see the main sections — and include a palm grove, an aroid and bamboo collection, a fruit-tree section with most of the regional commercial species (mango, lychee, longan, durian, dragonfruit, jackfruit), and a useful medicinal plants display with bilingual labels.
It is one of the quieter major attractions in the area and works well as an alternative to the beach on a hot afternoon — much of the visit is under shade. Bring water and bug spray. There is a small visitor centre near the entrance with maps and a café.