Abstract: A ramp unit for pontoon structures has two inner float bodies, each having an upper deck and a lower deck, and connecting hinges pivotally connecting the two inner float bodies to one another. Two outer float bodies each having an upper deck and a lower deck are connected respectively by double-jointed hinges to the two inner float bodies at a side of the two inner float bodies opposite the connecting hinges. A folding and unfolding mechanism folds the two inner and the two outer float bodies into a folded W-shape for transport and unfolds the W-shape into a stretched operating position in which the upper decks of the two inner and the two outer float bodies form a planar driving deck. Portions of each one of the lower decks of the two inner and the two outer float bodies are planar in a longitudinal direction of each of the two inner and the outer float bodies over the entire length thereof.