Multimillionaire Victor Vescovo committed himself to one of the world’s craziest remaining adventure quests: to reach the deepest points in every ocean. What does it take to get there? A radically high-tech, $30 million Triton submersible, a team of crack engineers and scientists, and one very gonzo explorer….

It was a Sunday in Tonga, so the kingdom’s business had come to a halt. Stores were shuttered, traffic was quiet, even the airport was closed. King Tupou VI strolled out of his oceanfront palace and down the main street of Nukualofa, capital city of the island of Tongatapu, to attend church along with the rest of his South Pacific nation. Men wore their best sarongs; women wore taovalas—coconut-fiber aprons—over long dresses. The scene was all very ordinary except for one thing, and it was visible from the palace’s front lawn: a 224-foot ship moored at the pier, bristling with heavy cranes, stacked with high-tech equipment, and carrying a mysterious $30 million cargo…