If it’s a national park in Hawaii, then it has to have something to do with 
beaches, waves and surfing, doesn’t it? Actually, no. On the island of Maui, a national park sweeps across the stunning landscape of Haleakala, a 10,023-foot volcano whose peak is surprisingly accessible and extremely popular.
Visitors can easily drive to the summit of Haleakala (which means “House of the Sun”), though it’s admittedly a steep trip into the clouds along an extended series of switchback curves. The 38-mile trip ascends from sea level to 10,000 feet in about two hours, during which you traverse three climate zones. There are three picturesque overlooks to enjoy – Leleiwi, Puu Ulaula, and Kalahaku – and a visitor center just below the peak.
More than one million people annually make this journey, many of them in the predawn hours as it’s a dramatic place from which to view the sunrise. The sunset views are pretty spectacular, as well. According to Hawaiian legend, it was here that the demigod Maui lassoed the sun from the summit of Haleakala in order to force it to move more slowly across the sky and thereby lengthen the day. 
At the top, one can look down into a massive crater that encompasses 19 square miles and is more than 2,600-feet deep. The Haleakala Crater was formed through the ages by erosion from wind and water. A number of breathtaking hiking trails lead down into the crater’s lunar landscape. The trails are breathtaking in more ways than one, though. Remember, if you begin by hiking down, it means you have to return by hiking uphill. Not always an easy task, especially at that altitude. There are, however, escorted hiking and horseback tours available. Or, you can take a van up to the peak and then enjoy an exhilarating ride back down the twisting road on a rented mountain bike.
Haleakala is also a prime location for astronomy and there are observatories located near the summit. These are unfortunately closed to the public, although a stargazing expedition can be arranged through a local company that brings portable telescopes up the mountain.
source: http://www.examiner.com/