I've seen some snapping turtles, one up close, attached to my friends lure. It was pretty big, and in an area I wade alot. I hate to admit it, but there are times I'm a little uneasy in my tube. I sometimes cringe when feeling something bump my leg (branches). The worst story I've heard though, and I'm serious. I was told by a friend, but I'm sure he was serious. A guy caught a musky, and when it got in close, it tore his leg up (maybe trying to chew the line?). Anyway, you can all laugh at me now, but really I have 2 tubes. One I'm in the water about up to my pits, and unless I'm in Aurora or some high mountain lake, I'm never that comftorable. My other one, I sit pretty high out of the water, but I'm worried about tipping over (setting the hook and all :-[). I seriously am going to try to tip that sucker over once the water warms up. Just to see how possable it is, and how easy it is to get out if it happens. Go ahead and laugh. I grew up in Michigan, and have been chased by water moccasins. Once camping in Allegan, MI. A girl we were swimming w/ got bit by a snapper near shore. Some guy had to cut it's head off to get it to let go. I'm going on here defending my uncomfortableness. I do have a suggestion. You can get nice kayaks set up for fishing for $250-$500. By the time you add up waders, fins, and wadding boots, it can actually be cheaper. Also, theres places that only allow wakless boats or that don't allow float tubes unless they're more than one chamber. I hope I haven't scared you more. once you're fishing you kind of forget about other stuff, well, until you see something.
