Europe is, by convention, one of the world's seven continents. Comprising the western most peninsula of Eurasia, Europe is generally 'divided' from Asia by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the water ways connecting the Black and AegeanSeas. Europe is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and the Black Sea and connected waterways to the southeast.
Yet the borders of Europe—a concept dating back to classical antiquity—are somewhat arbitrary, as the primarily physiographic term "continent" can incorporate cultural and political elements. Europe is the world's second-smallest continent by surface area, covering about 10,180,000 square kilometres (3,930,000 sq mi) or 2% of the Earth's surface and about 6.8% of its land area. Of Europe's approximately 50 states, Russia is by far the largest by both area and population, taking up 40% of the continent (although the country has territory in both Europe and Asia), while the Vatican City is the smallest.