Plot as I remember:
TV show in future. People promice to breathold UW for specific time, and they are forced to do so. They cannot reach air until time gone.
There is live TV broadcast during this, very popular show.
3 Brazilian sisters breath holding underwater together, it would be record time for this show, they did not have 3 people UW for so long time. But two systers did not manage it and drown. Third survided and won big prise.
I read this story 15? years ago.