User blog comment:Lord Loss/Discussion of the Week: Swimming/@comment-26074976-20130122203539/@comment-4517339-20130124041722

Fighting monsters while holding onto your breath would be increadably dificult.

And when the hunters get hit that would make adrenaline flow around their body. The heart would be the one sending it with every beat it takes. Absobing the remaining oxyden that was in your lungs.

In short. If you get hit then you will run out of breath very quickly. Making you go to the surface.