The park features the dormant Haleakalā (East Maui) Volcano, which last erupted at around 1790. The park is divided into two distinct sections: the summit area and the coastal Kipahulu area.
The two sections of the park averages 1,450,000 visitors per year.
The summit area includes Haleakalā Crater, the summit of the volcano, and the area surrounding the summit. This part of the park is accessed by Hawaii state road 378.
The main feature of this part of the park is undoubtedly the famous Haleakalā Crater. It is huge: 11.25 km (7 mi) across, 3.2 km (2 mi) wide, and some 800 meters (2,600 feet) deep. The interior of the crater is dotted by numerous volcanic features, including large cinder cones. Two main trails lead into the crater from the summit area: the Halemau'u and Sliding Sands trails. Hikers in the crater can stay in one of three cabins (which need to be reserved through the park first).
Each morning, visitors come to the summit of the volcano to watch the spectacular sunrise. More visitors come each afternoon to watch the equally amazing sunset. One attraction of the park is Hosmer's Grove, a unique forest of alien trees including deodar from the Himalayas, sugi from Japan, eucalyptus from Australia, and several species from North America (pine, spruce, cypress, fir, and others). Native plants and trees are also present in the forest but are not very common due to the little light available (because of the taller alien trees).
The park is known for its unique 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. The Hawaiian nene geese can also be seen in their natural habitat in Haleakala Crater. Although Nene 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 second section of the park is the Kipahulu section. 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. (The road goes in a complete circle along the southern coast, but the area of it directly west of Kipahulu is closed due to recent landslides. Check the park's website below for updates.) This part of the park lies within the lower part of Kipahulu Valley. It is separated from the summit area of the park by the upper portion of the valley. 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 ecosystem.
This section of the park features more than two dozen pools along Palikea Stream in the gulch called 'Ohe'o. These pools contain rare native freshwater fish. Visitors may choose to swim in these pools, or they may choose to hike a trail that takes visitors up to the base of Waimoku Falls.