Key Largo is one of Marathon’s eight identified exploration prospects in the Paleogene area, and perhaps the deepest ever at nearly 35,000 feet deep — 34,800 total measured depth, 34,082 feet total vertical depth.

And to get to the Wilcox objective, the drill bit will have to penetrate over 17,000 feet of salt.

“This is quite a significant well,” said Marathon vice president of worldwide drilling and completions Bryan Roy.