In the desert of South Australia there is a town where most of the population lives inside the rock. Not in caves — in houses. Bedrooms, kitchens, bathrooms, corridors, all cut horizontally into the side of a hill, because the surface regularly passes a hundred and fifteen degrees and has been recorded at nearly a hundred and nineteen.

Coober Pedy was dug for opal. Australia produces about ninety-five per cent of the world's precious opal, and this is the largest producer by weight in the country.

But the thing almost nobody mentions is what the census actually says. In the 2021 count, twenty people in Coober Pedy worked in opal mining. Fifty-nine worked in accommodation. The opal capital of the world now employs three times as many people in hotels as it does in the mines.

We look at how the dugouts work, what the ground does to the people who dig into it, why the town is emptying, and where the opal goes.