Some countries have a long coastline, but much of it may not be readily usable for trade and commerce. For instance, in its early history, Russia's only ports were on the Arctic Ocean and frozen shut for much of the year. The wish to gain control of a warm-water port was a major motivator of Russian expansion towards the Baltic Sea, Black Sea and Pacific Ocean. On the other hand, some landlocked countries can have access to the ocean along wide navigable rivers. For instance, Paraguay (and Bolivia to a lesser extent) have access to the ocean through the Paraguay and Paraná rivers.