Jastarnia is a resort town in Puck County, Pomeranian Voivodship, northern Poland. It is located on the Hel Peninsula on the Baltic Sea. …Jastarnia is a resort town in Puck County, Pomeranian Voivodship, northern Poland. It is located on the Hel Peninsula on the Baltic Sea. It is a popular Polish seaside resort and small fishing port. The place was mentioned as "Osternese" in 1582, which is derived from North Germanic.