[4] Haleakalā was originally part of Hawaii National Park along with the volcanoes of Mauna Loa and Kilauea on the island of Hawaiʻi, created in 1916.

The main feature of this part of the park is Haleakalā Crater which, despite its name, is geologically an erosional valley.

The interior of the crater is dotted by numerous volcanic features, including large cinder cones.

One attraction of the park is Hosmer's Grove, a unique forest of trees including deodar (Cedrus deodara) from the Himalayas, sugi (Cryptomeria japonica) from Japan, eucalyptus from Australia, and several species from North America (pine, spruce, cypress, fir, and others).

The park is known for its volcanic features, its long scenic drive with numerous overlooks, and the unusually clear views of the night sky available.

Haleakalā is one of the best places in the United States for amateur astronomy, and binoculars and telescopes are available for rent from many local merchants.

Although nēnē died out entirely in the park, in 1946 they were re-introduced with the help of the Boy Scouts, who carried young birds into the crater in their backpacks.

The park service has erected fences to prevent damage from local herbivores and from visitors taking the plants as souvenirs.

[18] Several species of native forest birds across Hawaiʻi are nearly extinct, including the kiwikiu and 'ākohekohe that are found only in East Maui, whose population decreased by more than 70% in the 21st century.

[19] The working group Birds, Not Mosquitos[20] joined with the National Park Service and the Hawaii Department of Land and Natural Resources to develop a plan to address the threat, eventually settling on the Incompatible insect model.

[21] As of 2024, each week some 250,000 male southern house mosquitos carrying Wolbachia bacteria were released on the mountain, totaling 10 million by June of that year.

Visitors cannot drive directly to this section from the summit area; they must take a winding coastal road that travels around the windward coast of the island.

This area is designated the Kipahulu Valley Biological Reserve and is closed to the public to preserve the native plant and animal species in this fragile rainforest.

It lies above the tropical inversion layer and so experiences excellent viewing conditions and very clear skies.

For over 40 years, the University of Hawaii Institute for Astronomy has managed this site, conducting dedicated astrophysical experiments.

One of its missions, the Maui Space Surveillance System (MSSS), tracks satellites and debris orbiting the Earth.

John W. Stratton 10/19/1961 – 5/11/1963 Neal G. Guse 7/01/1963 – 7/15/1967 Forrest M. Benson Jr. 8/27/1967 – 6/14/1969 Lynn H. Thompson 6/29/1969 – 11/16/1970 Russell Cahill 1/17/1971 – 4/27/1974 Hugo H. Huntzinger 5/26/1974 – 12/19/1987 Peter G. Sanchez 12/20/1987 – 3/26/1988 Donald W. Reeser 3/27/1988 – ?