Vitomir Maričić, a freediver from Croatia, managed to hold his breath for 29 minutes and three seconds at the bottom of a three-metre-deep pool, shattering the previous world record by a whopping five minutes.

Most of us can only hold our breath for a few seconds to a couple of minutes, but with the right training, some people can hold their breath underwater for such long periods of time that they might as well be superhumans.

These people are called freedivers. After undergoing extensive physical and mental training, including diaphragmatic breathing, cardiovascular exercise, and meditation, they are able to perform extreme feats that seem impossible to most humans.

Vitomir Maričić, an experienced freediver from Croatia, recently set a new world record for the longest oxygen-assisted breath-hold ever - 29 minutes and 3 seconds - surpassing the previous world record by approximately five minutes.

"It got worse and worse physically, especially for my diaphragm, because of the contractions, but mentally, I knew I wasn't going to give up," Maričić said after his monumental achievement "After the 20-minute mark, everything became easier, at least mentally."

When holding our breath, the oxygen level in our blood drops, and the carbon dioxide level rises. When the latter reaches a certain level, the body begins to involuntarily contract the diaphragm, the main muscle of breathing, triggering the involuntary reflex to breathe again.

When a "physiological break-point" is reached, the diaphragm contracts to force a breath, which can be lethal underwater. Luckily, freedivers are trained to fight this reflex until the very last possible moment.

Although diaphragmatic breathing and cardiovascular exercise are essential for freedivers, most of them also rely on meditation for mental discipline. They need to manage their fear and anxiety and maintain a calm mental state under extreme conditions, and reduce both mental and physical activity to decrease the rate at which oxygen is consumed.

Under normal conditions, Vitomir Maričić can hold his breath underwater for eight to 10 minutes, but in order to increase his breath hold, he breathes pure oxygen for about 10 minutes before going underwater. This allowed him to have five times the normal oxygen level in his blood, which helped him hold his breath for much longer.

However, breathing pure oxygen is dangerous because it can cause oxygen toxicity, which can be fatal.