Summary The ‘Devil’s Hole’ is a large active blowout that originated in the early 1940s at Ravenmeols Local Nature Reserve on the Sefton Coast dunes. Wind erosion produced two calcareous, seasonally-flooded, dune-slacks that are still growing. Their floristic development was studied between 2004 and 2022, annual changes being monitored from 2012. By 2022, a total...