BILOXI, Miss.-U.S. Coast Guard Lt. John Garr, the deputy branch director of on-water operations at the Incident Command Post in Mobile, Ala., describes the sub-surface oil assessment program with a reporter for the Mississippi Public Broadcasting Company, as a boat crew behind him demonstrates deployment of a snare sentinel in Biloxi Bay, Sept. 9, 2010. Sub-surface oil assessment is a critical step in the Deepwater Horizon oil spill response, allowing responders to thoroughly map, track and collect crucial underwater data. U.S. Coast Guard photo by Petty Officer 2nd Class Annie Elis.