Pacific Ocean: Bikini's Nuclear Ghosts; The Oceans; Scientific American Presents; by Zorpette; 4 Page(s)

I am at ground zero of the most powerful explosion ever created by the U.S. Forty-six meters (150 feet) underwater near the edge of Bikini Lagoon in the central Pacific, I am kneeling in the sand with a 27-year-old Majorcan divemaster at my side. At this moment, he's laughing into his scuba regulator at the sight of an array of big, five-pointed starfish on the seafloor, which evokes for him an American flag.

The divemaster, Antonio Ramon-Le-Blanc, and I have come to a place where very few have ever ventured: a submerged crater formed shortly before dawn on March 1, 1954, when the U.S. military detonated a thermonuclear bomb on a spit of sand jutting out from Nam Island, in the northwest corner of Bikini Atoll. The experts anticipated that this nuclear test, codenamed Bravo, would have an explosive yield equivalent to somewhere between three and six megatons of TNT. Instead they got 15 megatons, a crater 2,000 meters wide and a fireball that swelled far beyond expectations, terrifying the nine technicians left as observers in a concrete bunker 32 kilometers away.