Free divers swim to extreme depths underwater (the current record is 214m, more than 700 feet) without any breathing apparatus. Champions can hold their breath for extraordinary amounts of time—the record for women is nine minutes, and men 11.
I’m a doctor with a special interest in extreme environments, so was intrigued when I was asked to collaborate in an art project about freediving for the Wellcome Collection’s new exhibition Somewhere in Between. Scientists and those who practice freediving are in many ways utterly alien to one another. When you look at the stresses this sport places on our physiology, it initially looks almost impossible that anyone should be able to dive to such profound depths—and yet they do.
Unsupported, breathing only air, you could just about climb Everest without any additional support other than your protective clothing. That’s 9km (5.6 miles) or so above sea level. But when you go into the ocean actually things change much more quickly because of the rapid pressure differences.
If you descend only 10m (33 feet) into the ocean, you are subjected to another additional atmosphere of pressure: that’s twice as much pressure as you’ve been used to at the surface. And for every 10m beyond you get another atmosphere of pressure. That starts to manipulate your body, your anatomy and your physiology in quite profound ways, which actually make the endeavor of diving into the deep ocean uniquely difficult. Not only does it compress you and shrink the air-containing spaces in your body, but also it alters your physiology, alters the way the gases act within your bloodstream and how they act on everything, including your nervous system.