trail boat on sale at buy.com

this thing is great if you weigh less than 180 lbs for backpacking to remote lakes in the mountains.  It weighs only 3 lbs without the carry bag, way less than a float tube!  Also works great for a chair when you're napping on shore. 

http://www.buy.com/retail/product.asp?sku=200054521&adid=17662

wait..is good for 220lbs so you big guys can float in it too. 

I had one of these - let me tell you, it did not last very long. You really need to be careful - the material used is not the best...unless it's been upgraded recently.