Deep wading

Deep wading or deep fording is a technique used by some heavy semi-amphibious vehicles to traverse water that is several metres deep - the vehicle drives on the riverbed/lakebed/seabed and uses screens or a pipe (a snorkel) that reaches above the water surface for an air supply. The technique has been used by armoured military vehicles such as tanks and armored personnel carriers. Deep fording generally implies driving through water of such a depth that the vehicle is mostly or entirely submerged by the water, sometimes to several times the height of the vehicle itself, as well as a sealed crew compartment, complete with air supply for the crew. This makes it different from the less extreme "wading" done by many off-road vehicles which are simply fitted with a snorkel that is higher than the normal engine air intake, roughly level with the top of the cab. In these cases, the crew compartment is not watertight, and the snorkel provides air only for the engine. Thus maximum height is limited by the crew's need to breathe, and very rarely completely submerges the vehicle.