I think this video right here pretty much gives every reason you'd ever need to convince yourself you should have an amphibious vehicle. Full tilt right into the water, and then you just keep going. What's not to like?
The video calls the car an AmphiGator Jeep water car, but some Googling seems to show that the jeep-like amphibian here is a also called a WaterCar Panther, which may be a slightly different model?
That Honda V6-powered Panther seems pretty great, though I think they could have named it after some animal that actually likes being in the water, right? Do panthers even swim? I better send the intern down to the zoo with a steak around his neck to find out.
Either way, it's great. Also, this picture of one on the back of a yacht messes with your brain a little.