Arkhangelsk Oblast the south-west of the Oblast drains into the Kema River which belongs to the basin of the Caspian Sea. The area in the Onega River basin containing the biggest lakes in the oblast, such as Lake Lacha, Lake Kenozero, Lake Undozero, and Lake Kozhozero. The tundra of the Nenets Autonomous Okrug also contains a number of bigger lakes. The river basin of the Pinega is characteristic of the karst, with a number of caves in the region. The White Sea coast within the Oblast is split into the Onega Bay (where the Onega is the major tributary), the Dvina Bay
Arkhangelsk Oblast of the Northern Dvina and the Onega. The railroad construction gave the momentum to the population and exploitation of these areas. A branch from Konosha eastwards to Kotlas and further to Vorkuta was constructed in the 1940s to facilitate the transport of coal from the Komi Republic. From Kotlas, another branch continues south to Kirov. A branch from Obozersky to the west, to Onega and further to Belomorsk, was built during World War II to secure the transport of goods from the harbour of Murmansk to central Russia. A piece of railroad between Arkhangelsk and Karpogory was also built in