There were attempts as early as the 14th century to aid shipwreck victims with the Chinese training in resuscitation for the drowning, as well as in Portugal and Sweden in the 1690s ordering that ships should be sent to sea to rescue shipwreck survivors, but the first mention of lifeboats was in China where boats were used to rescue people from the rivers in 1737.[1]
The development of the seaplane meant that aircraft could be used to rescue people but was limited as they could not land or take off in heavy seas.
Helicopters overcame this problem as they were able to hover over the victim and give aid by dropping a line to them with either a basket or diver to assist their extraction.[2]
For offshore and far from coast rescues operations most countries rely on naval or coast guard ships for these operations.[citation needed]
For submarines which have got into difficulty there are highly-specialised rescue submarines and support ships such as the NATO NSRS and the US's deep-submergence rescue vehicle.
There are still smaller boats which may be used on inland waters such as lakes or estuaries where the waters are generally calmer and shallow. These boats are often hand powered.[according to whom?]
References
^Evans, Clayton: Rescue at sea, ISBN0-85177-934-4, Conway Maritime, 2003.