My team and I used deep technical diving techniques to explore the coral biodiversity of warships sunk in the 1946 nuclear bomb tests at Bikini Atoll.Our surveys revealed that eight nuked warships harbored 27 percent of the world’s coral genera on their hulls, superstructures and armaments.At depths down to 55 meters (180 feet), these ships lie well below the 21st-century ocean warming danger zone.As a result, Bikini’s massive warships have become unexpected arks of coral biodiversity. In our last Reefscape story, we explored the northern Marshall Islands in search of answers about the long-term effects of nuclear fallout on coral reefs. We visited Rongelap and Ailinginae atolls, where Cesium-137 and other highly radioactive material from 1954’s Castle Bravo hydrogen bomb test on Bikini Atoll had drifted downwind, falling like snow on the people, lands, and reefs.