In case you haven’t heard: Fran Crippen, an open-water swimmer on the U.S. national team, died this weekend during a 10K race in the UAE. There are still a lot of details that aren’t clear, but apparently the water was very warm and Crippen told his coach he wasn’t feeling well after 8K (that’s almost 5 miles).

It’s a horrible story, and it’s possible that he had a heart attack and would have had one regardless of whether he was swimming or not. But having a heart attack or passing out on the sidewalk is different than passing out in the water. And it sounds like what really happened was severe overexertion.

Elite athletes — like Crippen clearly was — are adept at pushing through pain, but it sounds like Crippen knew *something* was wrong, he just may not have realized how bad it was. This was compounded by the fact that apparently a swimmer must finish the last race to earn the points and prize money from the rest of the season. So he couldn’t just decide to sit this one out or quit early.

To me, this is a scary and terrible reminder that just knowing how to swim doesn’t make you safe in the water. Even if there is some kind of lifeguard, you have to be careful. In this case, there were obviously other swimmers around, plus there was a referee boat in the front and Jet Skis behind the last swimmer, but apparently no one saw what happened. Teammates were the first to notice he had not finished the race and went back to look for him.

So please remember your income for the year is not riding on you completing 10 more laps. Don’t swim by yourself, and if you feel terrible, stop. Unfortunately, I don’t think that was an option for Crippen.