When I was younger I use to challenge myself in the tub (don't act like you didn't do it too!) I would submerge myself underwater in the tub and hold my breathe. I think the longest before I started seeing stars was somewhere around one minute maybe a little longer.
This guy is one another level! Free diver Carlos Coste from Venezuela attempted to break his own record for the Longest distance swam underwater with one breath. Swimming means he is actually using energy and oxygen which is a lot harder than just sitting still in the bathtub or neighborhood pool and holding your breathe! LOL
Carlos finally broke his own record on a recent open water swim when he went 177 meters (580 feet 8.5 inches) on a single breath.