I didn't even know this was humanly possible': the woman who can descend into the sea on one breath
Ten years ago, Australian Amber Bourke was in her early 20s and backpacking through Egypt when she discovered something astonishing about herself. In a little village on the Sinai peninsula she came across a place that taught “free diving” – underwater diving without any breathing apparatus – and decided to give it a try.
“I held my breath for four minutes and I dove to 18 metres,” says Bourke, who is the current women’s Australian pool and depth freediving champion. “And both of those things, I didn’t realise was possible.”
Bourke had been a champion synchronised swimmer when she was a teenager, so already knew she could hold her breath for several minutes at a time. But discovering free diving “just opened my eyes to the possibilities … and I just got hooked on a feeling of diving deeper and wanted to see what I was capable of and how deep I could go.”
By 2018, Bourke had established herself as one of the best competitive free divers in the world, and in deep waters off the coast of the Philippines, was ready to attempt to break the women’s world record in the discipline of “constant weight no fins”.
Considered one of the most challenging forms of the sport, a diver descends vertically in deep water on a single breath, using only muscle strength to propel them downwards. With every metre of descent, the compressive pressure on the body increases, shrinking the spaces that contain air. By 30 metres down – the maximum depth physiologists in the early days of the sport thought humans were capable of reaching – the pressure exerted on the body is four times greater than on the surface and the volume of air inside the body has shrunk to one quarter. Once negative buoyancy is reached, the diver begins to freefall.
https://www.theguardian.com/society/2022/feb/06/i-didnt-even-know-this-was-humanly-possible-the-woman-who-can-descend-into-the-sea-on-one-breath
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The more firma, the less terra! 
