Novosibirsk Oblast (Russian: Новосиби́рская о́бласть, Novosibirskaya oblast) is a federal subject of Russia (an oblast). Its administrative center is the city of Novosibirsk. Novosibirsk Oblast is located in the southeastern Western Siberian plain, at the foothills of low Salair ridge, between the Ob and Irtysh Rivers. The region borders Omsk Oblast in the west, Tomsk Oblast in the north, Kemerovo Oblast in the east, and Altai Krai together with Kazakhstan (Pavlodar Oblysy) in the south. The territory of the oblast extends for more than 600 km (373 mi) from west to east, and for over 400 km (249 mi) from north to south. Novosibirsk Oblast is mainly plain; at south the steppes prevail; at north enormous tracts of woodland with great number of marshes prevail. There are many lakes, the largest ones located at the south. The majority of the rivers belong to the Ob basin, many of them falling in dead lakes. Largest lakes are Chani, Sartlan, Ubinskoye, and some others.