One of the mainstay tropes of fiction is sunken treasure: pirate treasure, ancient payrolls, treasure of the ancients... to quote The Goonies, "rich stuff". Gold. Gems. Artifacts. Stuff that would make Indiana Jones push his professorly duties off onto his overworked and underpaid grad students, grab his khakis, fedora, and bullwhip, and make a beeline for the middle of nowhere. However, since diving and its associated technologies have advanced over the years sunken treasures are growing more and more rare. Maybe there is only so much treasure to go around and a lot of it's been salvaged already. Maybe the …