Such formations number in the hundreds in Istria. In karst areas, a sinkhole, sink, or doline is a closed depression draining underground. It can be cylindrical, conical, bowl-shaped or dish-shaped.
Many sinkholes, depressions, or dolines exist in Istria's karst areas. These are closed depressions that drain underground and can take on various shapes like a cylinder, cone, bowl, or dish.