Kościerzyna is a town in Kashubia in Gdańsk Pomerania region, northern Poland, with 23,327 inhabitants as of June 2023. It has been the capi…Kościerzyna is a town in Kashubia in Gdańsk Pomerania region, northern Poland, with 23,327 inhabitants as of June 2023. It has been the capital of Kościerzyna County in Pomeranian Voivodeship since 1999; previously it was in Gdańsk Voivodeship from 1975 to 1998.