Grand Banks, submarine plateau rising from the continental shelf, c.36,000 sq mi (93,200 sq km), off SE Newfoundland, N.L., Canada. It is c.300 mi (480 km) long and c.400 mi (640 km) wide; depths range from 20 to 100 fathoms. The cold Labrador Current flows over most of the banks; the warmer Gulf Stream sweeps along the eastern edge, sometimes crossing the southern part. The Grand Banks are noted for the persistent dense fog (formed as warm air passes over the cold water) that engulfs the area. The mingling of the two currents along with the shallowness of the water forms a favorable environment for plankton and other small sea life upon which cod, haddock, halibut, and other fish feed. Lobsters are also found there. Fog, icebergs, and the nearby transatlantic shipping lanes make fishing hazardous. The Grand Banks were probably the world's most important international fishing ground until 1977, when Canada extended its offshore jurisdiction to include most of the area. Many of the commercial species, however, were overfished and depleted by the early 1990s. Oil drilling began on the banks in the late 1970s, but was slowed after the loss of the Ocean Ranger rig on Feb. 15, 1982.