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
Onega River mid-April - May. It was used for timber rafting. The Onega flows among the coniferous forests (taiga of spruce, pine, and larch), mostly among the swamps. There are only four bridges across the Onega: one in Kargopol on the road connecting Kargopol to Nyandoma, one in the village of Sorokinskaya, on "Onezhsky Trakt", the road connecting Kargopol to Plesetsk and Yemetsk, one combined road and railway bridge connecting Oksovsky and Severoonezhsk, and one railway bridge in Porog on the railway from Arkhangelsk to Belomorsk (no road traffic). Elsewhere, including the former district center of Konyovo, the Onega can only be