While the Gulf of Mexico has always been known for its offshore oil, it finds a place on this list because experts believe that there is a tremendous potential for more oil in deeper and further from the coast. It is estimated that there are about 13 billion barrels of unrecovered oil in the region in an area called as the Lower Tertiary. This area is 200 miles off the coast and stretches from Alabama to Mexico. It consists of probably the oldest rock formation, approximately 60 million years old, and poses a unique set of challenges to reach. When the formation is so old, it needs to be fractured before oil can be extracted and this is not an easy process because of a number of reasons. The primary concern is that no one has ever fractured rock in deep water before and for this particular extraction; massive amounts of hydraulic horsepower will be needed.
Given the recent oil extraction debacle, BP has not yet received approval to proceed with exploring this Lower Tertiary region to which it currently holds rights. However it is expected to proceed with approval in due course.