Kościerzyna County is a unit of territorial administration and local government in Pomeranian Voivodeship, northern Poland. It came int…Kościerzyna County is a unit of territorial administration and local government in Pomeranian Voivodeship, northern Poland. It came into being on 1 January 1999 as a result of the Polish local government reforms passed in 1998. Its administrative seat and only town is Kościerzyna, which lies 51 kilometres south-west of the regional capital Gdańsk. Its borders equal approximately the borders of the old Marquessate of Berent in the German Empire.