When the research vessel Sally Ride set sail for Santa Catalina Island to map an underwater graveyard of DDT waste barrels, its crew had high hopes of documenting for the first time just how many corroded containers littered the seafloor off the coast of Los Angeles. But as the scientists on deck began interpreting sonar images gathered by two deep-sea robots, they were quickly overwhelmed. It was like trying to count stars in the Milky Way. The dumpsite it turned out, was much, much bigger than expected. After spending two weeks surveying a swath of seafloor larger than the city of San Francisco, the scientists could find no end to the dumping ground.

When Californians learned in October that the waters off Santa Catalina Island once served as a dumping ground for thousands of barrels of DDT waste, the ocean science community jumped into action. A crew was swiftly assembled, shipping lanes cleared, the gears set in motion for a deep-sea expedition aboard the Sally Ride, one of the most technologically advanced research vessels in the country. By Wednesday, the ship was ready to leave San Diego and head for the San Pedro Basin, where 31 scientists and crew members will spend the next two weeks surveying almost 50,000 acres of the seafloor -- a much-needed first step in solving this toxic mystery that the ocean had buried for decades. "We want to provide a common base map of what's on the seabed at a high enough resolution," said Eric Terrill of the Scripps Institution of Oceanography, who is leading an effort made possible by the many scientists and federal officials who helped fast-track this expedition. "There were a lot of heroics pulled by quite a few people ... to make this happen."