In Slowanski National Park, always watch your step. Home to Europe’s largest moveable dunes, this Polish park is renowned for destroying everything in its path. Thousands of years ago, the Baltic Sea formed an enormous dune here. It was then overtaken by forests, which were in turn completely destroyed by fire. Once free from the plants, the sand began to move, and from this point on, nothing was resilient to its whims. Huge piles of quartz devoured forests, lakes, swamps – even human settlements.