The Mystery in the Hamakua Valleys: Exploring the Kohala Ditch

Deep inside the valleys on the north end of the Big Island of Hawaii exist tunnels through mountains, a surprising number of buildings, and a variety of other infrastructure. There are no roads or trails to these places, and the only reasonable access is by helicopter. But what are they for? How did it all get there? Why has no one else on the internet wrote about it? I made several multi-day backpacking trips to explore this remote, largely undocumented part of the island to discover its history and hidden infrastructure.