An improved watertight gate for use in a port or canal is described. The watertight gate generally comprising two gate leaves and associated with each gate leaf is a foldable support structure and a gate position controller. The gate position controller interacts with the foldable support structure so as to move the associated gate leaf between an open and a closed position. By employing the gate position controller and the foldable support structure to control the gates the efficiency of the watertight seal provided by the gate is independent of water pressure produced by the surrounding bodies of water. Adjustable mounts attach the foldable support structures. These adjustable mounts provide for adjustment of the alignment of the watertight gate so minimizing the problems of installation alignment and reduced efficiency through wear and tear.