9. EFV (Expeditionary Fighting Vehicle)
Though never running at full capacity, the EFV stands as the most aspirational effort to transform amphibious vehicle capability. Its intended performance characteristics—advanced armour protection and water speeds of 29 mph—pushed the envelope of amphibious vehicle design. Notwithstanding its ultimate abandonment, the program’s scientific successes—especially in fields of hydrodynamics and propulsion systems—have shaped the evolution of current amphibious vehicles. Its influence still shapes present amphibious vehicle capabilities and design philosophy.