Haleakala Crater
The park’s main attraction is the eroded depression found at the Summit District known as Haleakala Crater. And, undoubtedly, the island's best hiking is found here. If you're in good shape, do a day hike descending from the summit along Keoneheehee Trail (Sliding Sands Trail) to the crater floor. You might also consider spending several days here amid the cinder cones, lava flows, and all that loud silence. Entering the crater is like landing on a different planet. In the early 1960s, NASA brought moon-suited astronauts here to practice what it would be like to "walk on the moon." Tent camping and cabins are available with permits. On the 30 miles of trails, you can traverse black sand and wild lava formations, follow the blooming ahinahina (silverswords) path, and take in tremendous views of the big sky and burned-red cliffs.
The best time to go into the crater is summer when the conditions are generally more predictable. Be sure to bring layered clothing—and plenty of warm clothes if you're staying overnight. It may be scorching hot during the day, but it gets mighty chilly after dark. Bring drinking water, as potable water is available only at the two visitor centers. Overnight visitors must get a permit at park headquarters before entering the crater.