Kauai Backcountry Adventures offers a great activity of tubing down irrigation ditches of a non-active sugar cane farm. This sugar cane farm is no longer producing sugar cane but the ditches still have water running through them! This is a great way to see areas of Kauai that you normally wouldn't be able to see. Rain Forests, valleys, tunnels!
You are outfitted with gloves and helmets with lights attached. You can rent water shoes or bring your own. The water is chilly but I wore my bathing suit and it wasn't too bad. Make sure to have an underwater camera because you will get wet. You are bussed up with the rest of your group and get a history of the company and how they were started, as well as an overview of Hawaiian history.
This was fun. We tubed for about an hour going through 5 tunnels. You can go fast and slow depending on the current. After tubing, a picnic lunch is provided and you can go swimming at a natural swimming hole!