You can’t always count on finding water above ground in Australia. Some rivers flow through the sand beneath their beds and arid calcite crusts in Western Australia seal off water trapped in permeable rocks beneath. Yet, far from being sterile isolated pools, these calcrete aquifers are teaming with life. ‘It can be a really bustling metropolis down there’, chuckles Karl Jones from the University of Adelaide, Australia, describing how these subterranean waterways are home to hundreds of species of tiny diving beetle. But no one knew how the diminutive insects breathe. ‘Terrestrial diving beetles generally go to the surface and collect a bubble of air, take it underwater and consume oxygen from there’, says Jones. But with no obvious source of bubbles for the subterranean dwellers, Jones, Steven Cooper from the South Australian Museum and Roger Seymour, also from the University of Adelaide, were curious to know just how the intriguing mini-beasts breathe. They publish their discovery that the insects breathe through their skins in Journal of Experimental Biology.