Lake Mead

This version was an electronic reconnaissance aircraft used in Arctic conditions. It crashed into Lake Mead, during a research flight. The crew of five was able to scramble away before the plane sank. It has been located by sonar in 170 feet of water, largely intact except for 3 missing engines (number two, three and four). The flight was for a secret missile guidance system that allowed navigation by tracking of the Sun. A low pass over calm water with pilot error put it into the lake. The aircraft plummeted from high altitude down to as close to the lake as possible. Unfortunately, Captain Robert M. Madison lost his depth perception and plowed the huge plane into the lake at 230 mph. The impact tore off all but one of the engines and sent the plane skipping along the lake surface. When she eventually stopped, she began to take on water and started to sink. Fortunately, all of the crew was able to escape into life rafts and wait for rescue.
Source: http://www.advanceddivermagazine.com/articles/B29/B29.html