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
Port of Murmansk Arkhangelsk and St. Petersburg (later renamed Petrograd). However, after the blocking of the Ottoman Empire's straits of the Bosphorus and Dardanelles to outside shipping and blockading of the Baltic Sea port of St. Petersburg, the Russian Empire could only use the northern port of Arkhangelsk. This port had limitations: when winter presented itself, navigation and shipping of any sort came to a halt. Therefore, it was decided to build a new port. The chosen location was in Murmansk due to its ability to accommodate sea traffic year-round, proximity to existing communities and relative ease to connect it to the empire's