Thank you Changliann!
Krynica Morska is a town and coextensive municipality on the Vistula Spit in northern Poland with 1,364 inhabitants (2006). It received town rights in 1991.
Krynica Morska is the main tourist destination on the Vistula Spit. It has the smallest population of any urban commune in Poland. Because of the inclusion of mainly rural areas of the spit within its boundaries, it has the lowest population density of any town in Poland, with 11.74 persons/km². (source)
Thank you Mirek!