Atlantis (GC 699) is one of the largest oil fields in the deepwater Gulf of Mexico. It is located in southeastern Green Canyon protraction area in the Western Atwater Foldbelt. Construction of semi-submersible production unit, similar in design to BP's Thunder Horse platform, began in April 2003. Oil and gas is transported to shore via purpose-built pipeline infrastructure to the Mad Dog platform. First oil was achieved in October 2007 and commercial production began in December 2007.