Since the 1920s, many diverse amphibious vehicles 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 design, 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. It combined a boat-like hull with tank-like tracks. In 1931, he tested a scaled down version of his invention.[9]