Sanbonyoshi Seaplane Base

The facility was not an independent airport but the seaplane component of the original Haneda Airfield. Its closure was a result of military conversion during WWII, followed by the massive post-war expansion of Haneda Airport. The original, small airfield with its seaplane ramp was deemed inadequate and was completely obliterated to build the much larger runways and terminals of the modern Tokyo International Airport (Haneda).

The original site of the seaplane base no longer exists. The coordinates provided (35.541389, 139.759167) point to the Keihin Canal, adjacent to a small waterfront park called Sanbonyoshi Ryokuchi (三本葭緑地). The land where the ramp and facilities once stood is now buried under the reclaimed land that forms the western edge of the modern Tokyo International Airport (Haneda). The area is now a mix of airport infrastructure, active shipping channels, and industrial port facilities.

The designation 'Sanbonyoshi Seaplane Base' with ICAO JP-1372 is an unofficial, modern cataloging reference, likely from aviation databases or flight simulators. Historically, this was the seaplane facility of the original Haneda Airfield, which opened in August 1931. It was a critical piece of infrastructure for early Japanese civil aviation, serving as Tokyo's primary air hub. Japan Air Transport Co., Ltd. (a predecessor of modern Japan Airlines) operated services from here using seaplanes like the Dornier Wal and Fokker Super Universal on routes to destinations such as Shimoda and Shimizu. The base represented the dawn of combined land and sea air travel for the Tokyo region before it was absorbed into the expanding land-based airport.

None. There are no plans, and it is physically impossible, to reopen a seaplane base at this specific historical location. The site has been irrevocably transformed and is now an integral part of one of the world's busiest airports and a major maritime channel.