At 9:51 a.m. July 21, 1948, a B-29 Superfortress, weighing in at 104,556 pounds, took off from China Lake, California. It traveled to a test area near Lake Mead to conduct high-altitude atmospheric research. After the last measurements were taken, the pilot took the plane a little lower. Both the pilot and co-pilot thought they were around 400 feet above the lake’s surface, but the altimeter was reportedly off. Around 12:30 p.m. traveling at 230 miles per hour, the B-29 struck the water and sank to the bottom of Lake Mead where it still lies today.