At sea level one minute of arc along the equator or a meridian (indeed, any great circle) equals approximately (within a third of a percent) one nautical mile (1.852 km or 1.151 mi). A second of arc, one sixtieth of this amount, is about 100 feet or roughly 30 meters. The exact distance varies along meridian arcs because the figure of the Earth is slightly oblate (bulges a third of a percent at the equator).