Our family enjoyed this. One of the hand-dug tunnels was 1/4 mile long! Kauai Backcountry Adventures has exclusive access to the historic irrigation system of the former Lihue Plantation. This ditch and tunnel system that once irrigated vast sugar crops had been unused since sugar was taken out of production in 2000. In January 2003, Kauai Backcountry opened a section for exclusive tubing tours. The waters which originate near the top of Mount Waialeale, one of the wettest spots in the world, are channeled through ditches and tunnels hand-dug by plantation workers over a century ago!