Kuolajoki River (Russian: Куолайоки, Finnish: Kuolajoki) is a river in the south of the Kola Peninsula in Murmansk Oblast, Russia and in Lapland, Finland. It is 30 kilometres (19 mi) long. The area of its basin is 1,635 square kilometres (631 sq mi). The Kuolajoki River originates in the Lake Kuolajarvi in Russia and flows into the Tenniöjoki River in Finland. Its biggest tributary is the Kolsanoya River.