Abstract: A method and apparatus for monitoring for damage to or failure of a mooring system comprising mooring lines (2) or anchors of a moored vessel (1). The vessel has a mooring point (4) to which at least one mooring line is connected. The method involves determining the geographical position of a locating point (5) on the vessel remote from the mooring point (4) and determining the heading of the vessel. The geographical position of the mooring point (4) is then calculated from the determined position of the locating point and the vessel heading. The position of the mooring point (4) is compared to at least one expected position of the mooring point (4), in order to provide an indication of failure of a mooring line (2) or anchor. The method has the advantage that failure of the mooring (lines 2) or anchors can be detected without direct monitoring of the integrity of the mooring lines (2), which is typically expensive and uses equipment that is vulnerable to damage.