A foldable pontoon for securing movement with the use of the crossing equipment, which has a compact, modular design composed of float modules and equipped with self-aligned joining elements that stabilise these modules, is distinguished by the fact that when closed for transportation it forms a trailer or semi-trailer with a self-supporting chassis (3) being a uniform lower part of the trailer or semi-trailer and additional float modules being an upper part of a trailer or a semi-trailer, whereas in its open position a self-supporting chassis (3) of a trailer or a semi-trailer is at the same time a basic middle float module (4) of a pontoon, to which additional self-aligned single float modules or a series of combined float modules can be attached.