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There is some awesome amphibian cars!

An amphibious vehicle (or simply amphibian), is a vehicle or craft, that is a means of transport, viable on land as well as on water – just like an amphibian.
This definition applies equally to any land and water transport, small or large, powered or unpowered, ranging from amphibious bicycles, ATVs, cars, buses, trucks, RVs, and military vehicles, all the way to the very largest hovercraft. Classic landing craft are generally not considered amphibious vehicles, although they are part of amphibious assault. Nor are Ground effect vehicles, such as Ekranoplans. The former do not offer any real land transportation at all – the latter (aside from completely disconnecting from the surface, like a fixed-wing aircraft) will probably crash on all but the flattest of landmasses.

General technical notes
Apart from the distinction in sizes mentioned above, two main categories of amphibious vehicle are immediately apparent: those that travel on an air-cushion (Hovercraft) and those that don’t. Amongst the latter, many designs were prompted by the desire to expand the off-road capabilities of land-vehicles to an “all-terrain” ability, in some cases not only focused on creating a transport that will work on land and water, but also on intermediates like ice, snow, mud, marsh, swamp etc.. This explains why many designs use tracks in addition to or instead of wheels, and in some cases even resort to articulated body configurations or other unconventional designs such as screw-propelled vehicles which use auger-like barrels which propel a vehicle through muddy terrain with a twisting motion.

Most land vehicles – even lightly armored ones – can be made amphibious simply by providing them with a waterproof hull and perhaps a propellor. This is possible thanks to the vehicle’s volume usually being bigger than its displacement, meaning it will float. Heavily armored vehicles however sometimes have a density greater than water (their weight in kilograms exceeds their volume in litres), and will need additional buoyancy measures. These can take the form of inflatable floatation devices, much like the sides of a rubber dinghy, or a waterproof fabric skirt raised from the top perimeter of the vehicle.

In the case of the Land Rover pictured to the side, floats in the shape of oil-drums have been used to create a vehicle that will swim much like an improvised raft.
For propulsion in or on the water some vehicles simply make do by spinning their wheels or tracks, while others can power their way forward more effectively using (additional) screw propellor(s) or water jet(s). Most amphibians will work only as a displacement hull when in the water – only a small number of designs have the capability to raise out of the water when speed is gained, to achieve high velocity hydroplaning, skimming over the water surface like speedboats.

History
Some of the earliest known amphibious vehicles were amphibious carriages, the invention of which is credited to the notorious Neapolitan Prince Raimondo di Sangro of Sansevero or Sir Samuel Bentham (1781). The first known self-propelled amphibious vehicle, a steam-powered wheeled dredging barge, named the Orukter Amphibolos, was conceived and built by United States inventor Oliver Evans in 1805, although it is disputed to have successfully travelled over land or water under its own steam.

Although it is unclear who (and where and when) built the first combustion-engined amphibian, in all likelihood the development of powered amphibious vehicles didn’t start until 1899. Until the late 1920s the efforts to unify a boat and an automobile mostly came down to simply putting wheels and axles on a boat hull, or getting a rolling chassis to float by blending a boat-like hull with the car’s frame (Pohl, 1998). One of the first reasonably well documented cases was the 1905 amphibious petrol-powered carriage of T. Richmond (Jessup, Iowa, USA). Just like the world’s first petrol-powered automobile (1885, Carl Benz) it was a three-wheeler.

The single front wheel provided direction, both on land and in the water. A three-cylinder petrol combustion-engine powered the oversized rear wheels. In order to get the wheels to provide propulsion in the water, fins or buckets would be attached to the rear wheel spokes. Remarkably the boat-like hull was one of the first integral bodies ever used on a car.

Since the 1920s development of amphibious vehicles greatly diversified. Numerous designs have been created for a broad range of applications, including recreation, expeditions, search & rescue, and military, leading to a myriad of concepts and variants. In some of them the amphibious capabilities are central to their purpose, whereas in others they are only an expansion to what has remained primarily a watercraft or a land vehicle. The design that came together with all the features needed for a practical all terrain amphibious vehicle was by Peter Prell of New Jersey. His designed unlike others could operate not only on rivers and lakes but the sea and did not require firm ground to enter or exit the water. combined a boat like hull with tank like tracks. In 1931 he tested a scaled down version of his invention.

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