The Hydra class were a class of three paddlewheel steam sloops of the British Royal Navy. They saw active service variously in the Baltic during the Crimean War, against Ottoman forces in Syria and against slavers in West Africa. Latterly Hydra and Hecate were used for survey in the Mediterranean, the Pacific, Australia and the Atlantic, and thus their names were re-used for the Hecla-class survey vessels in the late 20th century. Two of the class were broken up after more than twenty-five years of service, and Hecla was sold for commercial use in 1863.