The Deepwater Horizon oil spill, which occurred in April 2010, is significant primarily because it was the largest accidental marine oil spill in history. The spill released approximately 4.9 million barrels of oil into the Gulf of Mexico over a period of 87 days, leading to extensive environmental and economic damage. The repercussions of the spill affected marine and coastal ecosystems and had lasting impacts on local communities, fishing industries, and tourism.
While the cleanup efforts were extensive, they did not prevent lasting damage, and the long-term environmental effects are still being studied. The company responsible, BP, did face fines and penalties, although the extent and distribution of these consequences have been subjects of debate. The Great Lakes do show signs of broader environmental impacts from oil spills, but they were not directly affected by the Deepwater Horizon incident. Thus, the most accurate statement regarding its significance is that it was the largest accidental marine spill in history.