As said by Pat Bradley, one amongst the cameramen that documented US atomic testing throughout the 1950s, the Wahoo and the Umbrella underwater explosions were much more incredible compared to the atmospheric nuclear explosion. Check out this dazzling video and pay attention to him telling his experience of living such explosions barely 2.5 miles away.
The 2.5 miles looked like a fine distance to have an underwater explosion. As the idea proved, it was not. The waves drenched the whole cargo vessel close to ground zero. The walls of water kept moving forward, building up huge waves that strike the island from exactly where Bradley and his co-workers were filming. The final wave, the highest of them all, enclosed the whole island. They rescued their selves by immediately climbing to several palm trees bringing their bulky film camera equipment.