You might also like:
FOR MANY PLACES WITH A RIVER (including here in Nelson, BC), a summer float is tradition. This tubing trip on the Hawaiian island of Kauai though looks to be a step above all. The route, which was once an irrigation system for a sugar plantation in the late 1800s, flows through rapids and caves and dense rainforest and takes about 3 hours to complete start to finish. Kauai Backcountry Adventures has exclusive access to the plantation (which is 17,000 acres) so you have to book through them if you want to take the journey.
Source: matadornetwork.com