New Zealander William Trubridge has reached depths never thought possible on the precipice of low oxygen.

In a sport where failure usually means blacking out, it is a freediver's daily life to contend with suffocation, narcosis, hallucinations, lactic acidosis, compressed lungs, and immense water-column pressure - all while diving into depths of ink black ocean.

Exquisitely written, Oxygen is a mind-altering and immersive coming-of-age story about a boy who grew up on a sailing boat, with the sea his classroom and playground. It is about fighting the trappings of life on land, and pushing the limits of human physiology, to become the world's greatest freediver.