The Arctic Ocean is the smallest and shallowed of the world's major oceans. It is also seen as the northernmost part of the all-encompassing World Ocean. Located mostly in the Arctic north polar region in the middle of the Northern Hemisphere, the Arctic Ocean is almost completely surrounded by Eurasia and North America. It is partly covered by sea ice throughout the year and almost completely in winter. The Arctic Ocean also appears in the villain tournaments, as one of the minor, yet efficient, locations of the series.