The Okinotorishima Island is the southernmost island in Japan, located at N 20°25 E 136°04. It's part of Ogasawara Village, Tokyo.
The island is about 1,700 km south of central Tokyo, and it takes roughly 4 days by boat to get there. It's also about 900 km away from the Chichijima Island of the Ogasawara Islands.
Its latitude is about the same as that of Hanoi and Honolulu, and longitude as that of Lake Biwa.
The island is actually a table reef shaped like an eggplant, about 4.5 km east-west and 1.7 km north-south. The reef's perimeter is 11 km and area is about 5.8 km2, which is as large as 107 Tokyo Domes.
Within the reef are two islets that remain above the sea surface even at high tide: Kitakojima and Higashikojima. They're surrounded by concrete seawalls that are about 50 m in diameter (including tetrapods).
The exclusive economic zone based on the baseline of the Okinotorishima Island is some 420,000 km2, larger than the country's land area.
Image Source: Office of Designated Remote Island Ports, Kanto Regional Development Bureau, Ministry of Land, Infrastructure, Transport and Tourism, "Okinotorishima Island Landscape"
(https://www.pa.ktr.mlit.go.jp/ritou/okilandscape/map.html)
Image Source: Brochure of the Keihin River Office, Kanto Regional Development Bureau, Ministry of Land, Infrastructure, Transport and Tourism
(https://www.ktr.mlit.go.jp/ktr_content/content/000090712.pdf)
The Okinotorishima Island is an atoll that developed on top of a steep seamount. It's located in the center of the Kyushu-Palau Ridge, which stretches north and south from Kyushu to Palau, and is the only seamount to reach the sea level other than Palau.
The island was formed over a submerged pre-Miocene volcanic island, which was then covered by over a 1,500 m thick layer of corals. These corals arrived from Okinawa and the Ogasawara Islands about 1,000 km away, and accumulated over 15 million years.
The coral reef is classified as a semi-table reef, and consists of a shallow area around the edges (reef crest) and a body of water within that's 3 to 5 m deep (reef lagoon).
The slopes of the island are steep, and 4,000 to 7,000 m deep. Its cross section is shaped like Mt. Fuji.
Chart Source: Tokyo Metropolitan Government Bureau of Industrial and Labor Affairs website, "Topography"
(https://www.sangyo-rodo.metro.tokyo.lg.jp/nourin/suisan/okinotorishima/about/)
The Okinotorishima Island is the only place in Japan that's south of the Tropic of Cancer. It enjoys a tropical climate with an annual average temperature of 26.8°C and a sea temperature of 27.7°C. Close to waters where typhoons occur, many of them pass through the island each year.
The waves are 1.3 m tall on annual average, and up to over 16 m during a typhoon, etc. The wind velocity is 6 m/sec. on annual average, but it can go over 50 m/sec. when a typhoon is approaching. This means it's the roughest waters in Japan.
The waters around the Okinotorishima Island is known to be the spawning grounds and migration route for bonito, tuna, and other fish. Valuable mineral resources such as manganese are also said to exist on the seafloor. Manganese contains copper, methane hydrates (which are expected to be an alternative energy source for petroleum), and other substances.
Discovered by the Spanish ship San Juan (there are various theories).
Named "Okinotorishima" and incorporated into the jurisdiction of the Tokyo Metropolitan Government's Ogasawara Branch.
Construction of a meteorological observing station and lighthouse started (suspended when the Pacific War started).
Put under the administrative authority of the United States.
Returned to Japan along with the Ogasawara Islands.
Designated as a Coastal Conservation Area according to the Coast Act.
A civil project started under the government's direct management, and seawalls, etc. were installed.
The Act on the Territorial Sea and Contiguous Zone was revised, and the Act on Exclusive Economic Zone and Continental Shelf was promulgated. An exclusive economic zone was established around the Okinotorishima Island.
The Coast Act was revised.
Designated as an area under the direct control of the country.
Direct control started with expenses fully covered by the country.
A protective structure was installed on the Higashikojima Islet as a measure against flying objects.
Operation of the Okinotorishima Lighthouse started.
A protective structure was installed on the Kitakojima Islet as a measure against flying objects.
The Act on the Development of Base Facilities and Preservation of the Low-Tide Line for the Promotion of Use and Conservation of the Exclusive Economic Zone and Continental Shelf was brought into force. Made a Designated Remote Island.
Construction of designated remote islands port facilities by the country started
Operation of a new observing base facility started
Source: Created by the Tokyo Metropolitan Government Bureau of General Affairs based on the website of Keihin River Office, Kanto Regional Development Bureau, Ministry of Land, Infrastructure and Transport, "Conservation of the Okinotorishima Island to Date" (https://www.ktr.mlit.go.jp/keihin/keihin00035.html)
The official website of the Tokyo Metropolitan Government