On March 1, 1954, the United States military tested nuclear bombs in the ocean around Bikini Atoll in the Pacific Ocean to see what kind of damage they would do to ships. The largest explosion was set off 90 feet underwater: nicknamed "Castle Bravo," the bomb blasted a crater 2 kilometers (more than 1.2 miles) wide in the coral reef and obliterated ocean life in the area. Smithsonian scientists surveyed the reef before and after the explosion to study how radiation impacts marine life—but the experiment lasted even longer than that. In 2008, scientists revisited Bikini Atoll and found that the reef had largely recovered from the devastation after it was left alone for 50 years. Read more about this incidental experiment and coral reef resilience.