Kociewie is a geographical and ethnographical region forming part of the East-Pomeranian Lake District, which has changed over the years many times. The present borders of Kociewie were determined on the basis of Kazimierz Nitsch's linguistic research.
The researcher divided the area of Kociewie into primary, covering the vicinity of Pelplin, and extended, where the Kociewie dialect is encountered. Today's Kociewie is about 3 thousand sq. km. Its east border is the ca. 100-km-long section of the Vistula from near Gruczno on the south to Czatkowy village, located north of Tczew. From the north the region is delimited by the line from Pszczółki – Trąbki Wielkie, Wysin, while the western border runs along Stara Kiszewa, Bartoszy Las, Czarna Woda, Szlachta, Śliwiczki, Drzycim, and then to Gruczno towards the Vistula. In administrative terms, Kociewie is situated in the Pomeranian Voivodeship (entire districts: Starogard and Tczew, part of the Gdańsk District: part of the Trąbki Wielkie Commune and the Kościerzyna District with the Communes of Liniewo and Stara Kiszewa) and in the Kuyavian-Pomeranian Voivodeship (most of the land in the Świecie District, part of the Śliwce Commune in the Tuchola District). There are nine towns in Kociewie: Tczew, Starogard Gdański, Skarszewy, Skórcz, Czarna Woda, Gniew, Pelplin, Nowe, and Świecie. Starogard Gdański is considered the region's capital.