What was the first mass-produced civilian amphibious automobile?

The first mass-produced civilian amphibious automobile was the Amphicar.

Designed by German engineer Hans Trippel, the Amphicar combined a boat-shaped watertight body with ordinary road-car controls. The Model 770 used a rear-mounted Triumph four-cylinder engine: its wheels drove it on land, while twin propellers pushed it through the water. The name itself blends “amphibious” and “car.”

Production took place in West Germany from 1960 to 1965, with cars marketed into the late 1960s. About 3,878 were built, making the Amphicar a genuine production automobile rather than a publicity prototype or a handful of custom conversions. Most were sold in the United States.

The vehicle was practical only in a limited sense. It reached roughly 70 mph on land but only about 7 mph on water, and owners had to pay close attention to sealing and lubrication. The wartime Volkswagen Schwimmwagen was produced in greater numbers, but it was military equipment, not a civilian automobile. Modern names such as the Aquada and WaterCar Panther came much later.