Crossroads-Baker nuclear test, non-copyright U.S. Air Force color photo taken 2.5 seconds after detonation over Bikini Lagoon, 25 July 1946. 23 kiloton bomb was suspended 90 feet underwater in 180 feet of water. Bikini Island is seen in the distance. A target array of discarded WWII battleships, captured from Germany and Japan, is dwarfed by the hollow column of water spray, steam, and cratered coral sand, which is surrounded by a Wilson condensation cloud produced in the in the humid air by the partial vacuum blast phase following the shock front. On the surface of the water, a white circle marks the shock wave radius, and is composed of water droplets thrown upward from the water surface due to the reflection of the underwater shock wave at the air-water inferface.