We know more about the surface of the Moon and Mars than we do about the ocean’s seafloor. With water encompassing 63.78 million square miles, the oceans cover 70 percent of the Earth’s surface, with the world’s largest body of water, the Pacific Ocean, covering roughly one third. The Pacific also boasts the deepest trenches, specifically Challenger Deep in the Mariana Trench near the Federated States of Micronesia. Given Challenger Deep’s inhospitable environment, no one has attempted to extensively record ambient sound at its full depth. That is, until now.