Pingo comes from the Iñupiaq word pinu, which means an individual round hill or a swelling. Pingos, then, are swollen ice hills. They form most notably on Canadian and Alaskan Arctic coastal lowlands, where they offer one of the few prominent features in an otherwise ﬂat landscape. A type of ground ice, pingos most often emerge on top of drained lakebeds where the underlying permafrost has thawed. As the once insulating lake water disappears, foundational soils below the old lakebed freeze, squeezing out residual water. Arctic ground temperatures freeze this free water, and hydrostatic pressure forces it upward, creating an ice dome covered with the lakebed’s soils. Pingos can grow to 150 feet in height and be a thousand or more feet in diameter. They may, however, have short lives. Pingo domes often rupture, giving them a volcanolike appearance and exposing the ice core, which can melt, causing the structure to gradually collapse.