German diver Tom Sietas, 35, has a lung capacity 20 per cent larger than the average man his size. This doesn't fully explain, however, how he can hold his breath for over 20 minutes.
Sietas and former world-record holder, Brazilian Ricardo Bahia, were dropped into clear side-by-side tanks at a competition in China. The tanks contained cool water — at just 5°C, the water helped the divers' bodies relax — which was slowly heated up to almost 40°C as they held their breaths.
The secrets to his success? Sietas doesn't eat for five hours before an event, then fills his lungs with pure oxygen. He claims this can add more than 10 minutes to his time. (Without the pure oxygen, he can still hold his breath for over 10 minutes.)
Sietas has several records to his name, both in static apnea, in which he holds his breath for a long time and in dynamic apnea, in which he swims a distance while holding his breath.
His unique talent was first discovered by a scuba instructor who marveled at Sietas' ability to stay under the water considerably longer than other divers.
The Mirror reports that static-apnea competitors "face potentially fatal risks as the heart rate increases significantly, causing what experts call the samba effect. This is when contestants start shaking as though they are dancing, due to insufficient oxygen in the brain. It can then lead to a blackout."
Don't try this at home.