The Marine Services Unit patrols over 80 square miles of waterways in Contra Costa County from Richmond to Discovery Bay. The primary goal of the Marine Services Unit is to protect the lives and property of people on the waterways of Contra Costa County by promoting boating safety through education and enforcement.

The Marine Services Unit is staffed seven days a week by highly trained Deputy Sheriff certified as Marine Enforcement Officers. Duties include providing boating safety education to the boating community, conducting search and rescue operations above and below water, enforcing laws and regulations governing the operation of vessels, responding to complaints of reckless vessel operation, conducting vessel accident investigations, providing assistance to disabled vessels, and maintaining a proactive approach towards the suppression of criminal activity observed or reported in a maritime environment. The Marine Enforcement Officers also provide an on-water security presence in and around critical infrastructure and key resources within Contra Costa County.

The Marine Patrol is actively involved in improving the water quality of the Delta by way of abandoned vessel abatement and removal.  Maintaining a close partnership with the California Department of State Parks, Division of Boating and Waterways, other allied maritime enforcement agencies and private businesses, the Marine Services Unit is recognized as a model agency throughout the State of California for derelict and abandoned vessel abatement in the Contra Costa County waterways.

The Dive Team is a key component of the Marine Services Unit. It was established to provide specialized support in handling underwater operations and missions. Comprised of Deputies and volunteers required to be certified as Public Safety Divers, the Dive Team responds to a variety of incidents to include underwater search and recovery of property, evidence, and bodies.