The invention relates to a cassette for a pontoon bridge, the cassette (1) comprising a main compartment (9), a pontoon (2) having an elastic cushion installed in the main compartment (9), a split bottom (3) of the main compartment (9) with movable lids configured to open under pressure of the extending pontoon (2) when the pontoon (2) is inflated such as to allow extension of the pontoon (2) outside the main compartment (9). The invention also relates to a pontoon bridge formed of a plurality of the cassettes (1).