Wakkanai Naval Seaplane Base

The base was closed and dismantled following the surrender of Japan at the end of World War II. As part of the post-war demilitarization of Japan under the Allied occupation, all Imperial Japanese military facilities, including this seaplane base, were decommissioned and abandoned.

The site of the former seaplane base has been completely repurposed and is now primarily occupied by the Onuma Bird Park (大沼バードハウス), a nature preserve and bird-watching sanctuary. The area around the southern shore of Lake Onuma, where the base's hangars, barracks, and slipway were located, has been returned to a natural state and serves as a public recreational area. While most of the military structures were removed after the war, some concrete foundations and remnants of the seaplane ramp may still be found by historical explorers, though they are largely overgrown and not officially preserved as historical monuments. The provided coordinates point to the lake itself, which served as the water runway.

The Wakkanai Naval Seaplane Base, located on the shores of Lake Onuma (大沼), was a strategic outpost for the Imperial Japanese Navy Air Service (IJNAS) during World War II. It functioned as a detachment base for the Ominato Air Group (大湊海軍航空隊), which was tasked with the defense and patrol of northern Japan. Its primary mission was conducting reconnaissance and anti-submarine warfare patrols over the strategically vital La Pérouse Strait (Soya Strait), the Sea of Okhotsk, and the waters surrounding Sakhalin (then known as Karafuto) and the Kuril Islands. The base was crucial for monitoring Soviet naval and shipping activity, particularly in the final year of the war. Operations were conducted using floatplanes and flying boats, such as the Mitsubishi F1M 'Pete' and Aichi E13A 'Jake', which utilized the calm waters of Lake Onuma for takeoffs and landings. The ICAO code 'JP-2683' is an unofficial identifier used in non-governmental databases to catalog historical airfields and is not an official ICAO designation.

There are no plans or prospects for reopening the Wakkanai Naval Seaplane Base. The site has been fully integrated into a public park and nature preserve for decades. The strategic and technological reasons for its existence are obsolete, as modern military and civilian aviation needs are met by conventional airports. The nearby Wakkanai Airport (IATA: WKJ, ICAO: RJCW) currently serves all air transportation needs for the region.