Lyon Arboretum is at 3860 Mānoa Rd., about 2.5 mi. n.w. of the University of Hawai‘i at Mānoa’s main campus. Though not located on campus, it is affiliated with the university and contains native Hawaiian, Polynesian and economically important tropical plants. The 194-acre rain forest can be damp and muddy; rain gear and walking shoes are recommended.