The geological structure of the region is visualized by the division of Eastern Beskidy in two landscape belts: lower, outer belt called Beskidy Lesiste and inner, higher called Beskidy Poloninskie. Along the border between those belts runs a watershed of Dniestr and Prut and of river Cisa basin.

The entire macroregion can be divided into 12 mezoregions: Sanocko-Turczanskie Mountains cut through by a Polish-Ukrainian border, Western Bieszczady, Eastern Bieszczady, Beskidy Brzezne, Gorgany, Beskidy Pokucko-Bukowinskie, Polonina Rowna, Borzawa, Polonina Krasna, Swidowiec, Czarnohora and Poloniny Hryniawskie.

A part of this region located within the Polish borders occupies the area of 2.5 thousands sq km and consists of two mezoregions (Western Bieszczady and Sanocko-Turczanskie Mountains). The Polish part of the mountains reaches only as high as 1346 m asl.

Sanocko-Turczanskie Mountains cover the area of around 930 sq km. This range is located in the outer part of Eastern Beskidy between the valleys of San and Stryja. Mountain ribs in this part of the mountains run parallel and their height increases in the south-eastern direction. San river encircles the south-western part of this range. As a result of building a dam, a so called Solinskie Lake was created. This water basin is a major tourist attraction in this region. Many holiday resorts have been established on its shores – the biggest ones are: Solina and Polanczyk Zdroj. The biggest town in this region is Sanok.

Western Bieszczady cover the area of 1560 sq km. This range is located between the Lupkowska Pass and Oslawa Valley in the west and Uzocka Pass and springs of San on the border with Ukraine. This region is sparsely populated and the biggest settlement in the mountains is Cisna village. The road network is also underdeveloped in this area which increases the ecological value of this part of Poland. Almost the entire area of Bieszczady Mountains is protected as a Bieszczady National Park and two landscape parks.