Here’s a good article on Waipio Valley the team at Hawaii.com which is a favorite on the Big Island Circle Tour.
In the beginning there was Waipiʻo Valley, a place of such sheer beauty that it could only have been conceived by the most benevolent and creative of all the gods of nature. Located north of the town of Honokaʻa along the Hamakua Coast, the valley is the largest and southernmost of the seven valleys on the windward side of the Kohala Mountains.
A mile wide at the coast and almost six miles deep, the Eden-like valley is sheltered by cliffs reaching almost 2,000 feet. Waterfalls and flowers cascade from the walls of the cliffs, and a stunning black sand beach defines the coastal area.
The Valley of the Kings
Waipiʻo, which means “curved water,” is known as the “Valley of the Kings” because it was once home to many early Hawaiian rulers and is said to be the place where King Kamehameha the Great received his training. Ancient burial caves are located in the walls of the cliffs and many ancient myths, chants and songs originate in Waipiʻo.
Taro Farmers and Fishermen
Once inhabited by an estimated 4,000 to 10,000 people, Waipiʻo is now home to only a handful of taro farmers and fishermen. The original settlers were Hawaiian, but in the late 1800s many Chinese immigrants came to live there. They built schools, churches, restaurants, a post office and a jail. Most of them left following a devastating tsunami in 1946 that pushed huge waves into the back of the valley. The most convenient and accessible view of the valley is from the scenic point at the end of Route 240, about 10 miles outside of Honokaʻa. While a visit to the valley floor has its obvious rewards, the view from the top holds plenty of merit. Tour operators are not allowed to take visitors to the beach.