Redwood City is host to the Bay's only deep-water port south of San Francisco. The Redwood City Police Department's Marine Unit is responsible for investigating crimes occurring on areas of the San Francisco Bay, south of the San Mateo Bridge. The Unit conducts marine rescues and educates people on marine safety issues. The Unit also tows abandoned boats and assists the U.S. Coast Guard and other agencies as needed. The Unit is staffed by specially-trained police officers and overseen by a police sergeant.