Air-sea rescue, and aeronautical and maritime search and rescue (AMSAR) by the ICAO and IMO, is the coordinated search and rescue (SAR) of the survivors of emergency water landings as well as people who have survived the loss of their seagoing vessel. ASR can involve a wide variety of resources including seaplanes, helicopters, submarines, rescue boats and ships. Specialized equipment and techniques have been developed. Both military and civilian units can perform air-sea rescue. Its principles are laid out in the International Aeronautical and Maritime Search and Rescue Manual. The International Convention on Maritime Search and Rescue is the legal framework that applies to international air-sea rescue.

Search and rescue (SAR) is the search for and provision of aid to people who are in distress or imminent danger. The general field of search and rescue includes many specialty sub-fields, typically determined by the type of terrain the search is conducted over. These include mountain rescue; ground search and rescue, including the use of search and rescue dogs ; urban search and rescue in cities; combat search and rescue on the battlefield and air-sea rescue over water.