The United States Coast Guard carries out three basic roles, which are further subdivided into eleven statutory missions. The three roles are:
The eleven statutory missions as defined by law are divided into homeland security missions and non-homeland security missions.
Non-homeland security missions include: Marine safety, search and rescue, aids to navigation, living marine resources (fisheries law enforcement), marine environmental protection, and ice operations
Homeland security missions include: Ports, waterways, and coastal security (PWCS); drug interdiction; migrant interdiction; defense readiness; and other law enforcement.
A given unit within the Coast Guard may be carrying out several missions at once. For example, a 25-foot (7.6 m) RHIB assigned to maritime security may also watch for out-of-place or missing aids to navigation, pollution, and unsafe boating practices.
Search and Rescue (SAR) is one of the Coast Guard's oldest missions. The National Search and Rescue Plan designates the United States Coast Guard as the federal agency responsible for maritime SAR operations in U.S. and international waters, and the United States Air Force as the federal agency responsible for inland SAR. Both agencies maintain Rescue Coordination Centers to coordinate this effort.
Inshore rescues are usually performed by 25-foot, 27-foot, and 41-foot (7.6 m, 8.2 m, and 12.5 m) boats. HH-60 and HH-65 helicopters serve on both the high seas and inshore.
Search and rescue operations are numerous and varied. A sample of operations in February 2005 included:
Large-scale search and rescue operations occur less frequently, but often involve many Coast Guard vessels and aircraft from a large area. Helicopters and rescue swimmers participated in the 36-hour rescue of six crew members from the 570-foot (170 m) tanker Bow Mariner, which exploded and sank off of Chincoteague, Virginia, on February 28, 2004. Two rescue swimmers were awarded the Coast Guard Medal for their extraordinary efforts to keep the rescued mariners alive.