1- Kuwait - 1991 - 520 million gallons
Iraqi forces opened the valves of several oil tankers in order to slow the invasion of American troops. The oil slick was four inches thick and covered 4000 square miles of ocean.
2 Mexico - 1980 - 100 million gallons An accident in an oil well caused an explosion which then caused the well to collapse. The well remained open, spilling 30,000 gallons a day into the ocean for a full year.
3. Trinidad and Tobago - 1979 - 90 million
During a tropical storm off the coast of Trinidad and Tobago, a Greek oil tanker collided with another ship, and lost nearly its entire cargo.
4. Russia - 1994 - 84 million gallons
A broken pipeline in Russia leaked for eight months before it was noticed and repaired.
5. Persian Gulf - 1983 - 80 million gallons
A tanker collided with a drilling platform which, eventually, collapsed into the sea. The well continued to spill oil into the ocean for seven months before it was repaired.
6. South Africa - 1983 - 79 million gallons
A tanker cought fire and was abandoned before sinking 25 miles off the coast of Saldanha Bay.
7. France - 1978 - 69 million gallons
A tanker's rudder was broken in a severe storm, despite several ships responding to its distress call, the ship ran aground and broke in two. It's entire payload was dumped into the English Channel.
8. Angola - 1991 - more than 51 million gallons
The tanker expolded, exact quantity of spill unknown
9. Italy - 1991 - 45 million gallons
The tanker exploded and sank off the coast of Italy and continued leaking it's oil into the ocean for 12 years.
10. Odyssey Oil Spill - 1988 - 40 million gallons
700 nautical miles off the cost of Nova Scotia.
SOURCE: Envirowonk and The Associated Press