Before revision: Geographical distribution upright=1.7| Continental shelves cover an area of about 27 million km2 (10 million sq mi), equal to about 7% of the surface area of the oceans.Continental shelf – Blue Habitats The width of the continental shelf varies considerably – it is not uncommon for an area to have virtually no shelf at all, particularly where the forward edge of an advancing oceanic plate dives beneath continental crust in an offshore subduction zone such as off the coast of Chile or the west coast of Sumatra.
After revision: '''==Geographical distribution== upright=1.7| Continental shelves cover an area of about 27 million km2 (10 million sq mi), equal to about 7% of the surface area of the oceans.Continental shelf – Blue Habitats The width of the continental shelf varies considerably – it is not uncommon for an area to have virtually no shelf at all, particularly where the forward edge of an advancing oceanic plate dives beneath continental crust in an offshore subduction zone such as off the coast of Chile or the west coast of Sumatra.