
Reuters
Fire boat response crews battle the blazing remnants of the offshore oil rig Deepwater Horizon, off Louisiana, in this April 21, 2010 file handout image.
BP's CEO Bob Dudley told BBC Radio 4's Today programme this morning that the "tragic accident," which killed 11 men and saw more than three million barrels of oil flow into Gulf waters, shook the company "to its core" and was "a near death experience" for the energy firm.
"Sometimes it takes a near death experience to radically change a company. It was a forced focusing down of what we do, it was this is what we need to do to survive," he said to Lord Browne, who was guest editor on the radio programme and who happened to also be a former BP executive.
The spill was so bad that it affected the shorelines of five states - Louisiana, Texas, Mississippi, Alabama and Florida - and caused catastrophic consequences for the ecosystems and local economies.
For example, take a look at the following pictures from 2010 when the spill first happened. This is what the sea looked like:

Reuters
And the local ecosystems are still trying to recover after the killed off a lot of fish and animals in the local areas:

Reuters
In 2012, BP accepted responsibility for the disaster and agreed to pay $4.4 billion (£3bn) to the US government to settle its criminal liability.
However, in total since then, various other fines, compensation and lawsuits have totalled nearly $40 billion (£27 billion) and BP has sold off more than $45 billion(£30 billion) in assets to cover the costs.