Rented by the BP Oil Company to drill an oil well in the Gulf of Mexico, the Deepwater Horizon drilling rig explodes on April 20, 2010. It sinks into the ocean and causes a gigantic oil spill. At issue is negligence in the maintenance and in the tests carried out. On September 19, after months of unsuccessful attempts, the spill is finally declared sealed. However, this incident has generated the largest marine oil disaster in history. Part of the "Butterfly Effect" series.