Oops, forgot a sentence. There is nowhere in the Gulf of Mexico that is not covered by the exclusive economic zones of Mexico and the USA.
Wasn't the plot of Frank Herbert's book "21st Century Sub" centered around US submarines collecting oil in underwater barges from secret oil wells within the territorial limits of some unfriendly countries? Been a long time since I read it. (In some editions, this book carried the title "The Dragon in the Sea.")
Herbert was much better known, of course, for the Dune series.
Jack