According to Pat Bradley, one of the cameramen who documented US atomic tests during the 1950s, the Wahoo and Umbrella underwater explosions were more amazing than a atmospheric nuclear explosion. Watch this stunning video and listen to him explaining his experience of living these explosions just 2.5 miles away.
2.5 miles seemed like a safe distance for an underwater explosion. As it turned out, it wasn't. The waves engulfed an entire cargo ship near to ground zero. The wall of water kept advancing, generating gigantic waves that hit the island from where Bradley and his colleagues were filming. The third wave, the tallest of them all, covered the entire island. They saved themselves by quickly climbing to some palm trees carrying their heavy film camera equipment.
The Wahoo underwater nuclear test happened on May 16, 1958. Umbrella exploded on June 8, 1958. According to Atom Central, this sequence is part of a new HD version of Atomic Filmakers— Hollywood's Top Secret Film Studio. You can watch this film on the GoDigital channel on Youtube. [Atom Central]