SAN FRANCISCO, CALIFORNIA—Maps and images created with 3-D Echoscope sonar, a technology developed by Coda Octopus, of the SS City of Rio de Janeiro and the SS City of Chester, have been released by the National Oceanic and Atmospheric Administration and its research partners. The SS City of Rio de Janeiro sank on February 22, 1901, after it struck jagged rocks near the Golden Gate, killing 128 of the 210 passengers and crew aboard the ship. Many of the passengers were Chinese and Japanese immigrants to the U.S. “Today the wreck is broken and filled with mud, and it is a sealed grave in fast, dangerous waters in the main shipping lanes,” explained James Delgado, Director of Maritime Heritage for NOAA’s Office of National Marine Sanctuaries. The SS City of Chester was also rediscovered last year, resting in the mud near the City of Rio. “The level of detail and clarity from the sonar survey is amazing. We now have a much better sense of both wrecks, and of how they not only sank, but what has happened to them since their loss,” said Robert Schwemmer, West Coast Regional Maritime Heritage Coordinator. For more on nautical archaeology, see "History's 10 Greatest Wrecks."