Q4000 is a multi-purpose oil field construction and intervention vessel ordered in 1999 by Cal Dive International, and was built at the Keppel AmFELS shipyard in Brownsville, Texas for $180 million.

The vessel provides a stable platform for a wide variety of tasks, including subsea completion, decommissioning and coiled tubing deployment, and she is specifically designed for oil well intervention and construction in depths of up to 3000 meters of water.

The design of the Q4000 includes the following features:[6] Q4000 was in the Gulf of Mexico participating in the response to the Deepwater Horizon oil spill.

The vessel was used to position the large containment dome and also to attempt the "top kill" in which large quantities of drilling mud were pumped down the Q4000 drilling pipe into the failed Deepwater Horizon blowout preventer valve (BOP) in an attempt to stop the flow of oil.

After removal of the failed riser and drill pipe on the Horizon BOP, a capping stack sealed the top of the well on July 15, 2010, stopping the flow of oil into the Gulf of Mexico.