While at Niagra Falls, we took the jet boat tour into the Class 4/5 rapids.  They used to go into the Class 6 (highest rating possible), but after a few dozen deaths, they have decided to not do that anymore.  We took the small waterproof camera.  The photos aren’t the best, but mostly because we kept getting drenched.  It is pretty amazing what the boats can do… they pretty much dance on the rapids.