A docking system is disclosed in which modules that are of integral, unitary structure may be joined to form a floating dock. Each module is made up of a deck and side walls to form a hollow chamber within which is disposed a flotation unit of a large-scale honeycomb made by joining plastic containers to each other and to the deck and side walls. A substantially isotropic tension member or system of tension members is joined to the bottom of the walls and cells to complete a module in which applied forces are shared by all elements. Apparatus for aligning and joining modules to form dock structures are described as are apparatus to ballast the structure and determine freeboard.