THERE’S NO EXPERIENCE on Earth like diving under the ice in Antarctica. On life support and in an uninhabited and extreme environment, it’s as close as you can get to a spacewalk while remaining on this planet. My diving work in the Antarctic’s Ross Sea was twenty years ago now, but the beauty of that experience will never leave me.

We cleared snow from the surface of the sea ice to let light through, like a giant skylight. Then we drilled a wide hole through two metres of ice.