A subsea connector comprises a female element (1) defining a parallel bore (2) adapted to receive a male element (3). First releasable locking means are disposed between elements (2) and (3) and comprise a sprung cage (6) in which balls (5) are retained for movement in tapered grooves circumferentially spaced around element (3). As the cage moves relative to element (3) balls (5) protrude from the cage to a greater or lesser extent to lock the elements together. Second locking means prevent relative movement between elements (1) and (3) in a locking release direction of the first releasable locking means. These second locking means comprise lock balls retained in an apertured body disposed between elements (1) and (2).