 Earth has a total surface area of about 501 million km2 ( 197 million sq mi ) . About 70 @.@ 8 % of the surface is covered by water , with much of the continental shelf below sea level . This equates to 361 @.@ 13 million km2 ( 139 @.@ 43 million sq mi ) . The submerged surface has mountainous features , including a globe @-@ spanning mid @-@ ocean ridge system , as well as undersea volcanoes , oceanic trenches , submarine canyons , oceanic plateaus and abyssal plains . The remaining 29 @.@ 2 % ( 148 @.@ 94 million km2 , or 57 @.@ 51 million sq mi ) not covered by water has terrain that varies greatly from place to place and consists of mountains , deserts , plains , plateaus , and other landforms . 
