I have taken guided kayaking tours in the Everglades, Vancouver Island, Acadia National Park, Hilton Head Island, and the San Juan Islands. I have also taken a couple of kayaking harbor tours. The Island Adventures tour on Kauai was by far the most intense. It is 2.5 miles upstream. The current is minimal and the wind is at your back, but the paddling is constant. The trip is on the Hule'ia river and it goes thru a wildlife preserve but the pace set by the tour leader prevents stopping to see a bird or an interesting plant. You will need to do 60+ strokes per minute or you will fall behind. On the plus side, Island Adventures is very safety oriented. In addition to the leader there were two other staff members kayaking with the group and a small power boat followed the group. The rappelling part of the trip was also very safety focused. However, our group had 26 guests so the rappelling took a very long time. There was a significant amount of time spent waiting for everyone in the party to rappel. If you are an inexperienced or infrequent kayaker I would not take this trip. If you want to try rappelling for the first time these would be the company to use. Safety is clearly a top priority.