There are plenty of aircraft that can be equipped with floats instead of wheeled landing gear. In the 1930s and 1940s, it was much more common to see aircraft aircraft take off from the water than today (for example, Pan Am’s famous Clippers flying boats as airport infrastructure didn’t exist yet or was in its infancy). Today, it’s mostly small aircraft like the Cessna Caravan, DHC-6 Twin Otter, Cessna 182/206, and others routinely equipped with floats or otherwise land on the water.