A man who obviously has a “girth” larger than the inner radius of a floating inner tube, appears to have gone through it unscathed, both for him and the inner tube.
The inner diameter of the tube is around a meter (I’m guessing this guy is bigger than a 40-in waist). If the tube part is 10 cm across, that’s about 8L of volume being submerged, displacing 8L of water, exerting ~80N of buoyancy force, or more than 17 pounds. Another way to look at it is if you filled the tube with water it would weigh that much. Is it reasonable that the man’s “spare tire” would hold that up? In addition to the malleability of flab, water is a pretty decent lubricant.