Abstract: The disclosure herein describes a floating deck for use in a liquid storage tank, which comprises a generally circular planar platform formed of a plurality of interconnected modular units made of cellular foam plastic; the modular units are of different shape and include at least: a first series of panels, each being in the form of a truncated triangle and a second series of panels, each having a shape that includes at least a parallelogram portion and a small triangular shaped portion outwardly projecting from one side of the parallelogram portion at the upper end thereof; the triangular-shaped portion has a dimension which corresponds to the truncated portion of the triangle of the first series of panels so as to form a continuous platform when both series of panels are interconnected to one another. Other shapes of panels are also disclosed.