Methods, systems, and apparatus for a fill port for a flexible container such as a flexible self supporting dewatering or marine structure. The container includes a flexible material having at least one opening and a fill port having an inner port body and an outer port body. At least one face of the inner and/or outer port body has a plurality of cellular surfaces with cavities that do not extend through the inner and/or outer port body on which they are positioned. The cavities receive a portion of the flexible material when the inner port body, the flexible material, and the outer port body are secured together and in use, thus minimizing stresses on the flexible material surrounding the fill port by equally distributing the forces acting on this material during the filling stage and thus reducing the risk of tears or failure to the flexible container.