Elevation
（重定向自Base elevation）
![Elevation histogram of the surface of the Earth – approximately 71% of the Earth's surface is covered with water.](/Images/godic/202412/23/Earth_elevation_histogram_2.svg1840.png")
![A sign at 8000 feet (2438 meters) in the San Bernardino Mountains.](/Images/godic/202412/23/SanBernardinoMountains8000feetsign1840.JPG")
![This image was generated by NOAA from digital data bases of land and sea-floor elevations on a 2-minute latitude/longitude grid (1 minute of latitude = 1 nautical mile, or 1.853 km). Assumed illumination is from the west; shading is computed as a function of the east-west slope of the surface with a nonlinear exaggeration favoring low-relief areas. A Mercator projection was used for the world image, which spans 390° of longitude from 270° West around the world eastward to 120° East; latitude coverage is ±80°. The resolution of the gridded data varies from true 2-minute for the Atlantic, Pacific, and Indian Ocean floors and all land masses to 5 minutes for the Arctic Ocean floor.](/Images/godic/202412/23/Earth_surface_NGDC_20001840.jpg")
![Part of a topographic map of Haleakala (Hawaii), showing elevation.](/Images/godic/202412/23/Topomapcropped1840.jpg")
The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic system, vertical datum). Elevation, or geometric height, is mainly used when referring to points on the Earth's surface, while altitude or geopotential height is used for points above the surface, such as an aircraft in flight or a spacecraft in orbit, and depth is used for points below the surface.