The environmental crisis began on April 20 with an explosion on an oil rig off the coast of Louisiana, killing 11 employees.
Two days later, the platform sank 1,500 metres beneath the surfrace carrying with it 2.5 million gallons of oil.
The British oil giant first tried to connect a tube between the platform and the well on the seabed, leaving the equivalent of 5,000 barrels of crude oil flowing into the sea every day.
BP then installed inflatable barriers on nearby beaches and bays in an attempt to prevent the oil from contaminating the river banks but with little success.
On May 8, BP tried another approach that had never previously been tested at these depths: it sent a submarine down to the leak to try to cap the leak with a large dome.
But that operation also failed, as highly methane crystals formed underneath, creating a real safety risk for the teams at the surface.
Meanwhile, planes circled above, pouring millions of litres of dispersants onto the slick. These products are toxic, but they help break up the oil, which makes it easier to clean up.
With every passing day, between 800,000 and three million litres of crude were estimated to be gushing into the Gulf of Mexico.
Two days ago, BP made a last ditch attempt to stop the leak with an operation known as “Top Kill”
But what exactly does that involve?
Several ships will be used to pump think mud down onto the leak through a drill pipe and into the blowout preventer that sits on top of the well. If done with the right pressure and the right density of the mud then it will stop the flow of oil.
Another pipe will then be used to pump cement, and plug the well. It it fails and if no solution is found, the leak could continue to flee until the oil deposit has run out.
That could take years and would spell environmental disaster for Lousiana’s coastline and the impact on its wildlife would be enormous.
While BP is counting the cost of this catastrophe, nature will also pay a very heavy price. In the Mississippi Delta, there are nearly 400 different types of animal and sealife, several of them are protected. Some experts say it could take up to 10 years for the ecosystem to recover.
Gulf oil spill: dealing with disaster