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
Onezhsky District Porog; there is regular passenger navigation. There is also limited passenger service on the Onega Bay. Onega is served by the Onega Airport which has weekly passenger flights to Arkhangelsk and to the "selo" of Purnema on the Onega Peninsula. Onezhsky District has a very high concentration of historical, archaeological, and architectural monuments. The district contains thirty-two objects classified as cultural and historical heritage by Russian Federal law, and additionally eighteen objects classified as cultural and historical heritage of local importance. Most of these are wooden churches and chapels. The monuments classified as historical and architectural heritage are the following: