a single breath of air they dive to depths that cannot otherwise be reached without technical just. tree divers are a medical phenomena thanks to special breathing techniques and years of training doris hold on can hold her breath for up to six months. apnea divers 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 of the fish people's secret. their abilities make free divers coveted objects for study. during tests the oxygen