December 1998 – Construction begins on the Deepwater Horizon, built by Hyundai Heavy Industries, in Ulsan, South Korea.
February 2001 – The rig is delivered and valued at more than $560m.
20 April 2010 – Explosion and fire on the Transocean drilling rig Deepwater Horizon licensed to BP; 11 were reported missing and approximately 17 injured.
The rig was drilling in BP’s Macondo project offshore Louisiana, beneath about 5,000ft (1,525m) of water and 13,000ft under the seabed. A blowout preventer, intended to prevent release of crude oil, failed to activate.
22 April 2010 – The Deepwater Horizon rig sinks in 5,000ft of water. Initial media reports suggest a five-mile-long oil slick is seen.
23 April 2010 – The US Coast Guard suspends the search for missing workers who are all presumed dead.
25 April 2010 – According to the US Coast Guard, remote underwater cameras report the well is leaking 1,000 barrels of crude oil per day (bpd). The agency approves a plan to have remote underwater vehicles activate a blowout preventer and stop the leak. Efforts to activate the blowout preventer fail.
26 April 2010 – BP’s shares fall 2% on fears the cost of cleanup and legal claims will hit the British supermajor hard.
27 April 2010 – The US Departments of Interior and Homeland Security announce plans for a joint investigation of the explosion and fire. The Coast Guard announces it will set ablaze the leaking crude to slow the spread of oil in the Gulf.
28 April 2010 – The Coast Guard says the flow of oil is 5,000bpd, five times greater than first estimated. Controlled burns begin on the giant oil slick.
29 April 2010 – US President Barack Obama pledges “every single available resource”, including the US military, to contain the spreading spill. Louisiana declares a state of emergency due to the threat of the state’s natural resources.
30 April 2010 – A top Obama aide says no drilling will be allowed in new areas, as Obama had recently proposed, until the cause of the Deepwater Horizon accident is established.
The US Justice Department announces that a team of lawyers is monitoring the spill. BP Chairman Tony Hayward says the company will take full responsibility for the spill, paying for all legitimate claims and the cost for the cleanup.
The US Interior Department orders safety inspections of all 30 deepwater drilling rigs and 47 deepwater production platforms.
1 May 2010 – The Coast Guard announces the leak will affect the Gulf shore.
2 May 2010 – Obama visits the Gulf Coast to see cleanup efforts first hand. US officials close areas affected by the spill to fishing for an initial period of ten days.
4 May 2010 – BP spuds the first of two planned relief wells in the Macondo exploration well.
5 May 2010 – BP successfully attaches a valve to the end of the broken drilling pipe at the Macondo well in a bid to end the flow of oil into the US Gulf.
6 May 2010 – BP confirms the arrival of three massive containment domes designed to collect much of the 5,000bpd leaking into the US Gulf from the Macondo blowout.
The US Department of Justice asks Transocean to preserve evidence in connection with the explosion and sinking of the rig.