down into the darkness without having to breathe. with just one single breath of air they dive to depths that cannot other. as be reached without technical assistance. trade divers are a medical phenomena thanks to special breathing techniques of years of training doris hova month can hold her breath for up to six months. apnea diverse set records that puzzle science. how does the body manage to go so long without life giving oxygen. researches at the university clinic and phone want to get to the bottom fish people's secret.