This region is divided into following macroregions: Pobrzeza Estonskie (Estonian Coast), Nizina Estonska (Estonian Lowland), Pobrzeze Ryskie (Ryskie Coast), Pobrzeze Zmudzko-Kuronskie (Zmudzko-Kuronskie Coast), Nizina Staropruska (Staropruska Lowland), Nizina Srodkowolitewska (Mid-Lithuanian Lowland), Wysoczyzny Zmudzko-Kuronskie (Zmudzko-Kuronska Plateau), Nizina Semigalska (Semigalska Lowland). Only the southern part of Nizina Staropruska is located within Polish borders.

Nizina Staropruska (Staropruska Lowland) within the Polish borders covers the area of around 2660 thousand sq km. This area is almost completely devoid of lakes and has a well developed system of valleys, unlike the neighbouring Masuria Lakeland District. Almost the whole region belongs to the river-basin of Pregola, only in the western part rivers Walsza and Drweca Warminska are tributaries of Pasleka.

The Polish part of the region can be divided into 3 mezoregions: Wzniesienie Gorowskie (Gorowskie Elevation), Rownina Ornecka (Ornecka Plain) and Rownina Sepopolska (Sepopolska Plain).

Wzniesienie Gorowskie is an isolated moraine plateau exceeding 100 m asl in height which covers the area of 1280 sq km. This region is divided by the border between two geobotanic divisions: Baltic and northern. The are is located far from the main routes and is sparsely populated.
Rownina Ornecka is located on the area of 225 sq km and stretches along Drweca Warminska river, south from Wzniesienia Gorowskie and north from Olsztyn Lakeland District. The area is covered mostly by pine forests with a narrow belt of alluvial forests. The biggest town in the area is Orneta (population: 8.5 thousands).

Rownina Sepopolska within Polish borders covers the area of 1160 sq km. This plain is a wide trough, rising on its rim to 80-100 m asl and lowering in the central point to 40-50 meters. The plain is also cut through by two river valleys of Lyna and Guber.

A shallow lake – Oswin (6.4 sq km, 3.5 meters deep) is located in the north-eastern part of the region. This lake with its surroundings is protected as a nature reserve "Jezioro Siedmiu Wysp" (The Lake of Seven Islands) and is a breeding site for over 110 species of birds.