Europe is a peninsula that makes up the western fifth of the Eurasian landmass. It has a higher ratio of coast to landmass than any other continent or subcontinent. Its maritime borders consist of the Arctic Ocean to the north, the Atlantic Ocean to the west, and the Mediterranean, Black, and Caspian Seas to the south. Land relief in Europe shows great variation within relatively small areas. The southern regions are more mountainous, while moving north the terrain descends from the high Alps, Pyrenees, and Carpathians, through hilly uplands, into broad, low northern plains, which are vast in the east.