The Hamadryad was a hospital ship which served the seamen of Cardiff from the 1860s until 1905. The vessel, a man-of-war with 46 guns, had been built at Pembroke Dock in 1823 but was never put into service. Although she was subsequently taken to Devonport to be fitted out she was never completed and was towed to Cardiff in 1866 to be converted as a floating hospital, with room for 50 in-patients. The ship was moored at a site donated by the Marquess of Bute, to the west of the entrance to the Glamorganshire Canal. In 1904 a new seaman's hospital was built ashore to replace the ship, and also as a memorial to mark Queen Victoria's Diamond Jubilee. The new Royal Hamadryad Hospital was formally opened on 29 June 1905 by the 4th Marquess of Bute. The redundant ship was towed to Bideford, Devon, to be broken up but the ship's bell and figurehead were preserved.