- A harbour airport, also known as a seaplane base or water aerodrome, is an airport located on the water, usually within a harbour or port. It typically serves as a base for seaplanes and amphibious aircraft, allowing them to take off and land on the water. Harbour airports are often found in coastal areas or regions with numerous lakes and rivers. They offer a convenient way for aircraft to access areas that may not have traditional land-based runways or airports.