The sport of freediving, where you dive as deep as you can on a single breath without using any breathing apparatus, is a competitive sport that's also part of the curriculum at a growing number of dive schools worldwide.
New Zealanders are pretty good at it too; William Trubridge holds two current world records, and Kathryn Nevatt is a previous world record holder who is recognised as one of the world's leading female freedivers.
Adam Skolnick was covering the Vertical Blue freediving competition for The New York Times back in 2013 and found himself at the centre of a tragedy when American freediver Nick Mevoli died while attempting to set a new American record.
In his book One Breath: Freediving, Death, and the Quest to Shatter Human Limits (Viking) he looks at the incredible demands that competitive freediving places on the human body.
