A large South Korean fishing trawler sank in the waters off Antarctica Sunday night, prompting a hasty rescue effort to save missing sailors from the frigid waters. At least five are dead, with an additional 17 missing and 20 rescued. Sailors are likely to survive less than 10 minutes in the area’s cold seas. The ship sank about 1,000 nautical miles from McMurdo Station in Antarctica, a U.S. research center, and nearby ships, including fishing vessels from New Zealand, aided in the rescue efforts. It’s not clear what caused the ship to sink, as the waters were described as relatively calm at the time.