HMS Hydra was the lead ship of her class of wooden steam paddle sloops of the British Royal Navy, launched in 1838 at Chatham Dockyard.

[3] Hydra then saw action during the Syrian War, as part of a squadron under the command of Commodore Charles Napier (the ships Powerful, Ganges, Edinburgh, Revenge, Benbow, frigate Pique, and steamer Gorgon) operating off the coast of Ottoman Syria.

In Admiral Sir Robert Stopford's report on the Anglo-Austrian-Turkish landings in September 1840 he noted that the steam vessels had been "eminently useful in constantly moving along a great extent of coast with troops and arms, and taking part in the attacks upon the different forts".

[2] From 2 December 1847,[2] under Commander Grey Skipwith she operated off south-east coast of America[3] where she captured the ships: She then undertook a cruise to the Cape Colony as a survey vessel.

Captain Peter Frederick Shortland[15] took command in 1866[3] for her most notable task — a deep-sea cruise in 1867–1868 in the Mediterranean and in the Atlantic Ocean, and a sounding from Aden to Bombay.