I've heard these gardens referred to in a few different ways, such as "National Tropical Botanical Gardens" "Botanical Garden" or as my daughters like to say the "Big Kahuna" Gardens. Their reference is due to Pi`ilanihale, a heiau thought to be the largest ancient place of worship in all of Polynesia. This is a big deal. As the center piece to the gardens it is massive. It was built or finished by the sons of the great ruler Piilani in the 1500s who united the island or Maui, built fishponds, paved roads and irrigation fields. Hence the name, "Piilani" "Hale" Hale means 'home of.' This dutiful sons also built the first roads from Hana to West Maui, one along the coast, one up and over Haleakala. What: A garden with plants important the Hawaiian (and all Polynesian) people. Here you can learn not only the nutritional but cultural relationships between the people and fauna. Of note is the world's largest collection of breadfruit cultivars, and the largest hala forests in the islands. ( I love the fact that hala trees can migrate up to ten feet to be closer to a mate.)
Details: You can do a self-guide hike on the 1/2 mile flat terrain, but don't. Pop for the tour, it will be well worth it.
Cost: $10 for self-guided, and $25 for guided tour. Call ahead to reserve your tour time and make sure they will be open. 808-248-8912