On the 20th April 2010 an oil spill started in the Gulf of Mexico, which was still releasing oil on the 29th of September that year.
This is the largest accidental marine oil spill in US history.
11 people died in the accident; in addition 500 turtles died and 64 dolphins died. 3,000 dead birds were found but there were doubtless more killed. There are no estimates on how many fish died. If the accident had occurred further out, in a less fragile ecosystem, then the impacts would have been less severe environmentally at least.
210 x 10^6 barrels of oil were released.
US$2.5 x 10^9 were lost on fishing with 78,597 square miles not allowed for fishing. Hotels close to the accident saw a big increase in business due to people arriving to help clean up the spill. A total of US£23 x 10^9 of damage was estimated to have been caused.
Further reading: http://www.bbc.co.uk/news/special_reports/oil_disaster