HMS Barnstaple was a Hunt-class minesweeper built for the Royal Navy during World War I.
The Aberdare sub-class were enlarged versions of the original Hunt-class ships with a more powerful armament. The ships displaced at normal load and at full load. They measured long overall with a beam of and a draught of . The ships' complement consisted of 74 officers and ratings.
The ships had two vertical triple-expansion steam engines, each driving one shaft using steam provided by two Yarrow boilers. The engines produced a total of and gave a maximum speed of . They carried a maximum of of coal which gave them a range of at .
The Aberdare sub-class was armed with a quick-firing (QF) gun forward of the bridge and a QF twelve-pounder (3-inch (76.2 mm)) anti-aircraft gun aft. Some ships were fitted with QF six-pounder () Hotchkiss guns or QF three-pounder () Hotchkiss guns in lieu of the twelve-pounder.
Barnstaple, the first ship of her name in the Royal Navy, was built by the Ardrossan Dry Dock & Shipbuilding Company at their shipyard in Ardrossan. The ship was launched on 20 March 1919. She was sold on 1 December 1921. She served as Lady Cynthia after major modifications as a coastal steamship with the Union Steamship Company of British Columbia, Canada from 1925 to 1957.