Beaches are ever-changing parts of the world’s landscape, where waves and wind relentlessly punish rocks and minerals into fine grains of sand. But they are far from uniform around the globe, varying in size, shape, and topography, blanketed in soft sand, smooth pebbles, rocky outcrops or more rarely, shells. The overall colour of a beach depends on its composition. The bleached skeletons of millions of coral give Indonesia’s famous white beaches their ghostly cast, whereas Hawaii’s Black Sand Beach is made of finely ground volcanic lava.