Lake Mead, the largest water reservoir in the United States, has hit historic, record-low water levels due to an ongoing, multi-decade mega-drought in the American West. As the reservoir's waterline plummets—now sitting nearly 19 stories below its high-water mark—the receding waters have exposed a massive graveyard of long-lost artifacts, including sunken houseboats, speedboats, and even a World War II-era landing craft.