The semi-submersible Deepwater Horizon rig was moved into position and drilling in the Macondo Prospect began in Feb 2010, in almost 5000ft of water over the Mississippi Canyon in the Gulf of Mexico.
As final arrangements for completing the well were being made, an explosion on 20 Apr caused a huge fire on board. It ran out of control and on 22 Apr, the rig sank, rupturing the steel riser pipe (which had been previously filled with heavy drilling mud in an attempt to stem the flow of oil), causing a massive spill with ensuing environmental and economic damage.
The well was finally capped after several attempts on 15 Jul and the spill was completely stopped on 4 Aug 2010.