Vastitas Borealis

Vastitas Borealis (Latin, 'northern waste' ) is the largest lowland region of Mars. It is in the northerly latitudes of the planet and encircles the northern polar region. Vastitas Borealis is often simply referred to as the northern plains or northern lowlands of Mars. The plains lie 4–5 km below the mean radius of the planet. To the north lies Planum Boreum. A small part of Vastitas Borealis lies in the Ismenius Lacus quadrangle.

The region was named by Eugene Antoniadi, who noted the distinct albedo feature of the Northern plains in his book La Planète Mars (1930). The name was officially adopted by the International Astronomical Union in 1973.

The North Polar Basin lies within Vastitas Borealis, while Utopia Planitia, another very large basin, is adjacent to it. Some scientists have speculated the plains were covered by an ocean at some point in Mars' history and putative shorelines have been suggested for its southern edges. Today these mildly sloping plains are marked by ridges, low hills, and sparse cratering. Vastitas Borealis is noticeably smoother than similar topographical areas in the south.