So what's so special about a small ditch on the roadside? Well, this 50-foot-long ditch in the town of Waimea, Kauai holds an incredible secret. It was engineered to channel water from the Waimea River to the taro patches in lower Waimea Valley. And its engineering is what baffles archaeologists because it's planned in a way that is not found in any other place in Hawaii! The Menehune Ditch now is much smaller than early accounts describe. A fraction of it is visible today. The blocks used in creating the bridge (all 120 of them) are neatly cut smooth blocks of basalt stones which were somehow transported from a quarry 7 miles away. Directions to the ditch from Kaumualii Highway in Waimea town: turn onto Menehune Road and keep driving until you see the ditch on the left and the swinging bridge on the right.