After 58 Marines were rescued from the wreck of the Cheonan off the coast of South Korea, 46 people are still unaccounted for. South Korea has deployed military divers, boats, and planes as part of the rescue effort, but hope for any survivors is dimming—fierce waves and high winds are making rescue operations difficult. The Cheonan sank Friday after an explosion shut down its engine and killed power. One survivor told relatives about the terrifying ordeal, saying he heard a huge boom behind him that split the ship apart. A witness on another ship says “Yells and screams filled the air….Marines on deck were desperately shouting: ‘Save me!’” Though North Korea’s military has recently threatened “unpredictable strikes” against South Korea and the United States, officials say there is nothing yet to indicate that it is responsible for the explosion.