The oil spill from the Deepwater Horizon oil rig in the Gulf of
Mexico is the latest episode in a familiar story of polluted waterways,
destroyed ecosystems and devastated communities.

Since
1940 there have been over 60 major spills with an accumulated amount of
1.7 billion gallons of oil spilled on land and sea ( view
infographic). Yet despite this latest episode of what could
yet be one of the worst environmental disasters in U.S. history, there
are still calls to open up more offshore drilling in locations that will
present even greater challenges in the event of a spill – and as
history has shown us again, and again, it is not a matter of if, but a
matter of when.
Source: http://wwf.panda.org/wwf_news/features/offshore_oil_a_very_messy_business/