One of the coolest things we did in Hawaii was on the island of Kauai. At an old plantation in Lihue we went tubing the ditch with Kaua’i Backcountry Adventures.
The ditches were made in the late 1800’s for a sugar plantation’s irrigation system.
With about 10 of us in our group we geared up (helmet with a light, gloves and water shoes) and hopped into our tubes!
The water was cold and at some points we were moving pretty quick. We went through a total of about 5 tunnels. In one of the tunnels we all turned off our headlamps and floated through in complete darkness.
Definitely a cool experience and way more exciting than your average lazy river!