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thumb|, which functioned as a seaplane carrier for two months in 1913
thumb| about 1918
A seaplane tender is a boat or ship that supports the operation of seaplanes. Some of these vessels, known as seaplane carriers, could not only carry seaplanes but also provided all the facilities needed for their operation; these ships are regarded by some as the first aircraft carriers and appeared just before the First World War.
Terminology
thumb|RAF seaplane tender 1502, in 2011
In maritime parlance a tender is a vessel that is used to support the operation of other vessels.
In British usage, the term tender was used for small craft, with the term depot ship being used for large seagoing vessels. Flying boats and float planes even when based at home in ports and harbour had a need for small support vessels to operate.
British tenders were small craft of launch to pinnace size. These were used to ferry crews, stores and supplies between shore and the aircraft, to maintain the buoys used to mark out "taxiways" and "runways" and to keep these clear of debris to prevent foreign object damage, and in the case of emergency to act as rescue craft and airport crash tenders. Another early seaplane carrier was , an old cruiser converted and commissioned with a flying-off deck in mid-1913. However, HMS Ark Royal was the first ship in history designed and built as a seaplane carrier in 1914.
First World War
thumb|The Japanese seaplane carrier conducted the world's first naval-launched air raids in September 1914.
In the Battle of Tsingtao, from 5 September 1914, the Imperial Japanese Navy seaplane carrier conducted the world's first naval-launched air raids from Kiaochow Bay. The four Maurice Farman seaplanes bombarded German-held land targets (communication centers and command centers) and damaged a German minelayer in the Tsingtao peninsula from September 1914 until that November, when the Germans surrendered.