The mooring line device may be used for watercraft mooring to for example a dock. A bag may have a first wall, a second wall, two side walls, a bottom wall and a top wall with the top wall having an aperture. A hook may be disposed in the aperture with an attachment element protruding from the bag. The two side walls and the bottom may have a continuous opening with a closure device. A rope at a proximal end may be attached to the hook. A strap may be attached to one of the first or second walls and may be disposed to retain a rope when the rope is folded for storage in the bag.