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
Battle of Bolshie Ozerki of the intervention to involve American forces, though they successfully defended their camp from a Russian attack at Romanovka composed of forces that greatly outnumbered them two months later and inflicted hundreds of casualties during the Suchan Valley Campaign the following month. Allied forces began to withdraw rapidly from northern Russia shortly thereafter. Bolshie Ozerki was a small village situated between the port city of Onega and an important Allied position at Obozerskaya Station, along the Arkhangelsk-Vologda railroad. Because the port of the main Allied base at Arkhangelsk froze every winter, reinforcements had to be brought overland to the front