Many modern tanks and armored personnel carriers have an amphibious mode in which a fabric skirt adds buoyancy, and the tracks provide motive power.
The most famous such vehicle in World War II was the DUKW Amphibious Truck. It was deployed in the Pacific theatre to establish and supply beachheads. It was designed as a wartime project by Sparkman and Stephens, the famous yacht design firm.
Second best known is the German Schwimmwagen designed by the Porsche engineering firm in 1938 and widely used throughout the war. The amphibious bodywork was designed by Erwin Komenda, the firm's body construction designer, using the engine and drivetrain of the Kübelwagen.
See also amphibious assault ship