After leaving the Haleakala National Park Visitor Center at mile marker 20.5 on Hwy 378, you'll definitely want to head up to the summit. Turn left out of the visitor center parking lot and at mile marker 21 you'll come to another intersection. You'll want to take a right to reach the parking lot for the summit (the left road takes you to visit Science City and the observatories, but they are off limits to the public). The summit parking lot is built in the shallow crater of Pu'u 'Ula'ula (Red Hill). This should not be confused with Pa Ka'oao or "white hill" which is located below near the Visitor Center. Before you walk up the ramp to the summit look around you and observe some of Pele's fiery missiles. These chunks of lava were catapulted through the air during eruptions and hardened on their trip to the ground. The largest chunk is roughly four to five feet across.
Pu'u 'Ula'ula is the highest point on Haleakala. Climb the steps to the shelter or take the more gradual ramp from the far end of the parking lot. If you look to the southeast you will probably see the high summits of Mauna Loa and Mauna Kea Volcanoes on the Big Island, each over 13,000 feet in elevation, poking their summits through the clouds. Here, Haleakala's summit elevation is 10,023 feet, but the mountain was once much higher than this. A number of factors have contributed to Haleakala's shrinking, including thousands of years of erosion, rapid caldera collapse, and slow island subsidence (sinking into the ocean bed). It can be concluded that the summit of Haleakala at one time in the distant past probably reached an elevation of 13,000 to 14,000 feet, higher than the modern day volcanoes on the Big Island. As you look to the southwest, just outside the park on the next cinder cone of the rift, you will see Science City which you passed by earlier. Unfortunately, it is primarily off limits to the public and none of the high altitude observatories allow visitors. Scientists use the observatories to track satellites, measure the wobble of the moon, and conduct other space research. The summit of Haleakala is the altar of the sun. Many brave tourists choose to drive the highway in the wee hours of the morning in hopes of catching a Haleakala sunrise. However, many people are unprepared for what they find at the summit, bone-chilling cold and sometimes gusty winds. Some misguided tourists try to bear the 20-40 degree cold armed only with summer clothes and a hotel towel. Those unfortunate shivering sunrise visitors can thank the demigod of Mau'i for the slow pace of the sun. As you may have noticed on the sign entering the park, Mau'i is snaring La, the sun god. He did so for his mother Hina, who needed more hours in the day for her tapa cloth to dry. Using twine, Mau'i snared La and made a deal with him to "walk" more slowly across the sky from that day on.