The Ballad Of Ron Allum

In late March 2012, an oblong lime-green submersible broke the surface of the Western Pacific near Guam. On the deck of a nearby ship, the Mermaid Sapphire, an 80-person support team and a film crew cheered wildly. The team winched the peculiar-looking craft on board and released the hatch. The door swung open and, to even louder cheers, James Cameron, the legendary Hollywood action-film director, emerged. He had just dived nearly seven miles to the deepest point in the ocean, becoming the first...