a large floating platform assembly is assembled from a plurality of identical , relatively small modules each comprising a tubular member which is open at one end and has a flat head at the opposite end . the modules are secured together in a side - by - side arrangement at their headed ends to form a continuous flat platform of the desired area with the tubular members projecting downwardly from the platform into the water to receive water into their lower ends and form trapped pockets of compressed air beneath the entire area of the platform on which the platform is supported . the trapped air chambers may be interconnected to increase stabilization of the platform .