Waipiʻo Valley is located on the Hamakua coast of the Big Island of Hawaiʻi. "Waipiʻo" means "curved water" in the Hawaiian language. Waipi'o valley was the capital and permanent residence of many early Hawaiian. The valley floor at sea level is almost 2,000 ft (610 m) below the surrounding terrain. A steep road leads down into the valley from a lookout point located on the top of the southern wall of the valley. The road gains 800 vertical feet (243.84 m) in 0.6 miles (0.9 km) at a 25% average grade, with steeper grades in sections. This is a paved public road but it is open only to 4 wheel drive vehicles. It is the steepest road of its length in the United States [2] and possibly the world. The shore line in the valley is a black sand beach, popular with surfers. A few taro farms are located in the valley. Several large waterfalls fall into the valley to feed the river which flows from the foot of the largest falls at the back of the valley out to the ocean. A foot trail called Waimanu or Muliwai Trail leads down a steep path to the Waimanu Valley, which is not accessible by automobile. At upper end of the valley, Waimanu Gap at 2,089 feet (637 m) elevation leads to the south end of Waimanu Valley. The valley was the site of the final scene in the 1995 sci-fi film Waterworld, at which the main characters found dry land. Source:https://en.wikipedia.org/wiki/Waipio_Valley