Its more like this.... You have been swimming for 36 hours straight. Your back is sunburnt. You are starting to hallucinate and can barely keep putting one hand out before the other. All the while you are crossing shark infested waters. And you run across a fellow swimmer that is drowning. If you determine that you can pull him three miles to safety, you know that you have only hours to get out of the water before the sharks come out for their evening meal.
We ain't got no stinkin' sharks in Michigan. On the other hand Lake Superior doesn't get above 34F ever, so your point is taken.