Izu Islands

The Izu Islands (伊豆諸島 Izu-shotō) are a group of volcanic islands stretching south and east from the Izu Peninsula of Honshū, Japan.[1] Administratively, they form two towns and six villages; all part of Tokyo Prefecture. The largest is Izu Ōshima, usually called simply Ōshima.

Although usually called the "Seven Islands of Izu" (伊豆七島 Izu Shichitō) in Japanese, there are in fact more than a dozen islands and islets. Nine among them are currently inhabited.

Map of Izu Islands
Map of the Izu Islands


Shikinejima from Kōzushima. Furthest: Ōshima; left: Toshima; right: Niijima; smallest: Jinai-tō.

The Izu islands stretch south-east from the Izu Peninsula on Honshu and cover an area of approximately 301.56 km2 (116.43 sq mi). There are nine populated islands with a total population of 24,645 people (as of 2009) spread over 296.56 km2 (114.50 sq mi). The largest of them is Izu Oshima (8,346 inhabitants, 91.06 km2 (35.16 sq mi)), the smallest Toshima (292 inhabitants, 4.12 km2 (1.59 sq mi).)[2] Of the inhabited islands, seven are traditionally referred to as the "Izu Seven": Oshima, Toshima, Niijima, Kozujima, Miyakejima, Hachijojima, and Mikurajima, though Shikinejima and Aogashima are sometimes included as well. [2]

Left: Walls built by exiles on Hachijojima
Right: A beach on Niijima

Hachijojima tamaishigaki 2007-03-20
Niijima Habushi Beach

Each of the islands has its unique character: Oshima is noted for its active volcano Mt Mihara and camellias, Hachijojima for its former penal colony, Mikurajima for dolphin watching, Niijima for its numerous beaches, Kozujima for its white sandy shores, Hachijojima for its well-preserved unique culture, and Miyakejima for the 2001 volcanic eruption.[2]

During the Edo period, Nii-jima, Miyake-jima, and Hachijō-jima served as places of exile for criminals.

The subtropical Ogasawara Islands, which are also administratively part of Tokyo, lie further to the south. They form a far-flung archipelago of over thirty (30) islands some 1,000 km (621 mi) due south of Tokyo.


Image Name
Peak Name Coordinates
Landsat IzuOshima Island.jpg Izu Ōshima
91.06 8472 764 Mihara 34°44′N 139°24′E / 34.733°N 139.400°E
Landsat Toshima Island.jpg To-shima
4.12 304 508 Miyatsuka 34°31′N 139°17′E / 34.517°N 139.283°E
Utone shima.jpg Udone-shima
0.4 - 1) 210   34°28′21″N 139°17′38″E / 34.47250°N 139.29389°E
Landsat Niijima and Shikinejima Island.jpg Nii-jima
(with Hanshima
and Jinai-tō)
23.87 2420 432 Miyatsuka 34°22′N 139°16′E / 34.367°N 139.267°E
Shikine-jima aerial.jpg Shikine-jima
3.9 600 109 Kambiki 34°19.5′N 139°13′E / 34.3250°N 139.217°E
Landsat Kozushima Island.jpg Kōzu-shima
18.48 1914 574 Tenjō-zan 34°13′N 139°9′E / 34.217°N 139.150°E
Landsat Miyakejima Island.jpg Miyake-jima
55.44 2382 815 Oyama 34°5′N 139°32′E / 34.083°N 139.533°E
Ohnoharajima mlit1978.jpg Ōnohara-jima
0.2 - 114 Koyasu 34°02′53″N 139°23′02″E / 34.04806°N 139.38389°E
Landsat Mikurajima Island.jpg Mikura-jima
20.58 313 851 Oyama 33°52.5′N 139°36′E / 33.8750°N 139.600°E
Inambashima mlit.jpg Inamba-jima
0.005 - 74   33°38′53″N 139°18′08″E / 33.64806°N 139.30222°E
Hachijo Subprefecture
Landsat Hachijojima Island.jpg Hachijō-jima
62.52 8363 854 Nishiyama
33°7′N 139°47′E / 33.117°N 139.783°E
Hachojyo-kojima mlit1978.jpg Hachijō-kojima
3.08 - 2) 616.8 Taihei-zan 33°7′31″N 139°41′18″E / 33.12528°N 139.68833°E
Landsat Aogashima Island.jpg Aogashima
8.75 192 423 Maruyama
32°27′29″N 139°46′04″E / 32.45806°N 139.76778°E
Bayonaise Rocks mlit.jpg Bayonnaise Rocks
--- Myōjin-shō
0.01 - 9.9   31°53′14″N 139°55′03″E / 31.88722°N 139.91750°E
Smithisland milt.jpg Sumisu-tō
0.03 - 136   31°26′13″N 140°02′49″E / 31.43694°N 140.04694°E
Tori-Shima Island of Izu-Islands Aerial photograph.2001.jpg Tori-shima
4.79 - 3) 394 Iō-zan 30°28′48″N 140°18′22″E / 30.48000°N 140.30611°E
Soufuiwa.jpg Sōfu-iwa
0.0037 - 99   29°47′39″N 140°20′31″E / 29.79417°N 140.34194°E

1) Udone-shima was inhabited during the Meiji era.
2) Uninhabited since 1969 (then population 31, with a peak of 513)
3) Tori-shima, the largest of the uninhabited islands, had a population of 150 until 1902, when all were killed by a volcanic eruption. Since then, the island has been uninhabited.

Administrative divisions

The Izu Islands are divided into two towns (Oshima and Hachijojima) and six villages (remaining inhabited islands.) Three subprefectures are formed above the municipalities as branch offices of the metropolitan government.[2]

All the islands (more than a dozen in total) lie within the Fuji-Hakone-Izu National Park.[2] The four southernmost islands are not administrated under any town or village in Hachijō Subprefecture, but are unincorporated areas. Torishima is now uninhabited but is an important bird refuge.

Deserted islands between Aogashima and Ogasawara Islands, namely Bayonaise Rocks (Beyonēzu Retsugan), Smith Island (Sumisu-tō), Torishima, and Lot's Wife (Sōfu-iwa) do not belong to any municipality, because both Hachijō Town and Aogashima Village claim administrative rights. They are directly controlled by Hachijō Subprefecture instead.


Though the population on the Izu Islands has been dropping, the phase is less dramatic than on other isolated Japanese islands.[2]

Population changes[2]
Year Izu
1960 38,707 923,062 94,301,623
1970 32,539 736,712 104,665,171
1980 31,902 630,536 117,060,396
1990 30,032 546,505 123,611,167
2000 28,756 472,312 126,925,843
2005 26,242 422,712 127,767,994


The primary industries are fisheries, agriculture, and tourism. The most scenic spots on the islands are crowded with tourists during summers. Popular tourist activities include swimming, scuba diving, surfing, fishing, bird watching and trekking.[2]

Transportation between the islands, by cargo-passengers boats, jetfoils, and aircraft, is supported by harbours on all inhabited islands and five airports (small islands can be reached by helicopter).[2]

There are 5 airports, 15 harbors, and 19 fishing ports. Flights from Tokyo take 30 minutes, while boats take 7–10 hours and jetfoils make the route in about two hours. Transportation on the islands is considered important to the quality of life, why about 215 km (134 mi) of paved main roads serve a kind of vehicles.[2]

There was no electricity on the islands before 1953, but by 1962, 98% of the area receives electricity.[2]


The islands occupy the northern portion of the Izu-Bonin-Mariana Arc which extends to the Izu Peninsula and Mount Fuji on the Honshū mainland which are northern extensions of the Izu volcanic arc. The Izu arc ends there at a tectonic triple junction.

Volcanic activity is frequent in the area.[3] 31 people were killed when the research vessel Kaiyō Maru no 5 was destroyed during the 1953 eruption of Myōjin-shō. Volcanic activity, including the release of harmful gases, forced the evacuation of Miyake-jima in 2000. Residents were allowed to return permanently to the island in February 2005 but were required to carry gas masks in case of future volcanic emissions.[2]

To handle the various types of natural disasters threatening the region, including tsunamis, storm, floods, and volcanism, Tokyo metropolitan government has developed prevention and safety measures, including hazard maps and evacuation guidance, radios, signs, and a transport system for emergency supplies.[2]


A chain of volcanic islands, the Izu Archipelago are oceanic islands that formed relatively recently (within a few million years) without any previous connection to mainland Japan. In contrast to isolated Pacific islands, such as Hawaii and the Galápagos, the Izu Islands are located near the mainland and have thus been frequently colonized by various species by overseas dispersal from the mainland or from adjacent islands. This make them interesting for the studies of ecological and evolutionary processes.[4]

Campanula (Bellflower) colonized the entire archipelago in a single event. Similarly, the Euhadra snails, endemic to Japan, populated the islands in a single event and all individuals on inhabited islands possess an identical haplotype. The Apodemus mice, on the other hand, colonized the islands from the mainland in two independent events.[4]

See also


  1. ^ Nussbaum, Louis-Frédéric. (2005). "Izu Shotō," Japan Encyclopedia, p. 412.
  2. ^ a b c d e f g h i j k l m Gotoh, H.; Maeno, Y.; Takezawa, T.; Murata, T.; Takahashi, N. (2010). "Infrastructure maintenance and disaster prevention measures on isolated Islands: the case of the Izu Islands near tokyo". In Favro, S.; Brebbia, C. A. (eds.). Island Sustainability. WIT transactions on ecology and the environment (Vol. 130). WIT Press. ISBN 978-1-84564-434-5.
  3. ^ Volcanoes of the Izu, Volcano and Mariana Islands
  4. ^ a b Kuriyama, Takeo; Brandley, Matthew C.; Katayama, Akira; Mori, Akira; Honda, Masanao; Hasegawa, Masami (2011). "A time-calibrated phylogenetic approach to assessing the phylogeography, colonization history and phenotypic evolution of snakes in the Japanese Izu Islands" (PDF). J. Biogeogr. 38: 259–271. doi:10.1111/j.1365-2699.2010.02403.x.
  • Teikoku's Complete Atlas of Japan, Teikoku-Shoin Co., Ltd. Tokyo 1990, ISBN 4-8071-0004-1

Coordinates: 34°44′N 139°24′E / 34.733°N 139.400°E

Aogashima, Tokyo

Aogashima (青ヶ島村, Aogashima-mura) is a village located in Hachijō Subprefecture, Tokyo Metropolis, Japan. As of 1 October 2018, the village had an estimated population of 169, and a population density of 28.2 persons per km². Its total area is 5.96 square kilometres (2.30 sq mi).

Fuji-Hakone-Izu National Park

Fuji-Hakone-Izu National Park (富士箱根伊豆国立公園, Fuji-Hakone-Izu Kokuritsu Kōen) is a national park in Yamanashi, Shizuoka, and Kanagawa Prefectures, and western Tokyo Metropolis, Japan. It consists of Mount Fuji, Fuji Five Lakes, Hakone, the Izu Peninsula, and the Izu Islands. Fuji-Hakone-Izu National Park covers 1,227 square kilometres (474 sq mi).Rather than being a specific spot, the park is a collection of dispersed tourist sites that dot the region. The farthest point south, the isle of Hachijō-jima, is several hundred kilometers from Mount Fuji. The park includes a variety of geographic features including natural hot springs, coastlines, mountainous areas, lakes, and more than 1000 volcanic islands. Vegetation in the park ranges from species of mountainous trees to the subtropical vegetation of the Izu Islands.Fuji-Hakone-Izu National Park was established on February 2, 1936 as Fuji-Hakone National Park, and is one of the first four national parks established in Japan. In 1950, the Izu islands were added to the park, and its name changed to its present designation. Due to its proximity to the Tokyo metropolis and ease of transportation, it is the most visited national park in all Japan.Nearby cities include Odawara, Fuji, Minami Ashigara, and Numazu.

Hachijojima Airport

Hachijojima Airport (八丈島空港, Hachijōjima Kūkō) (IATA: HAC, ICAO: RJTH) is a regional airport serving Hachijōjima in the southern Izu Islands, Tokyo, Japan.

Hachijō Subprefecture

Hachijō Subprefecture (八丈支庁, Hachijō-shichō) is a subprefecture of Tokyo Metropolis, Japan. The organization of government belongs to the Tokyo Metropolitan Government Bureau Of General Affairs. Hachijō includes the following towns and villages in the Izu Islands:

Hachijō (town on Hachijō-jima and Hachijō-kojima)

Aogashima (village on Aogashima)The subprefecture has an area of 78.6 square km, with a population of 8,790.

Additionally, Hachijō includes the four southernmost Izu Islands, which are uninhabited. These islands currently do not belong to any municipality; both Hachijō and Aogashima claim administrative rights. From north to south, the islands are:

Bayonnaise Rocks (Beyonēzu Retsugan)

Smith Island (Sumisu-tō)


Lot's Wife (Sōfu-iwa)Among the islands of the subprefecture, only Hachijōjima and Aogashima are inhabited.

Hachijō language

The small group of Hachijō or Hachijōjima dialects are the most divergent form of Japanese or form an independent fourth branch of Japonic. They are spoken on the southern Izu Islands south of Tokyo, Hachijō Island and the smaller Aogashima, as well as on the Daitō Islands of Okinawa Prefecture, which were settled from Hachijō in the Meiji period. Based on the criterion of mutual intelligibility, Hachijō may be considered a distinct Japonic language.

Hachijō dialects retain ancient Eastern Japanese features, as recorded in the 8th-century Man'yōshū. There are also lexical similarities with the dialects of Kyushu and even the Ryukyuan languages; it is not clear if these indicate the southern Izu islands were settled from that region, if they are loans brought by sailors traveling among the southern islands, or if they might be independent retentions of Old Japanese.

Inejiro Asanuma

Inejiro Asanuma (浅沼 稲次郎, Asanuma Inejirō, December 27, 1898 – October 12, 1960) was a Japanese politician and leader of the Japan Socialist Party. Originally a right-winger in the 1930s, Asanuma was unusual in post-war Japan for his forceful advocacy of socialism, his support of the Chinese Communist Party, and his criticism of U.S–Japanese relations, which was particularly controversial.

Asanuma was assassinated with a yoroi-dōshi, a traditional sword, by ultranationalist Otoya Yamaguchi while speaking in a televised political debate in Tokyo. His violent death was seen in graphic detail on national television, causing widespread public shock and outrage.

Izu-Ogasawara Trench

The Izu-Ogasawara Trench (伊豆・小笠原海溝, Izu-Ogasawara Kaikō), also known as Izu-Bonin Trench, is an oceanic trench in the western Pacific Ocean, consisting of the Izu Trench (at the north) and the Bonin Trench (at the south, west of the Ogasawara Plateau).It stretches from Japan to the northern most section of Mariana Trench. The Izu-Ogasawara Trench is an extension of the Japan Trench. Here, the Pacific Plate is being subducted beneath the Philippine Sea Plate, creating the Izu Islands and Bonin Islands on the Izu-Bonin-Mariana Arc system.It is 9,780 metres (32,087 ft) at its deepest.

Izu Ōshima

Izu Ōshima (伊豆大島, Izu-ōshima) is an inhabited volcanic island in the Izu archipelago in the Philippine Sea, off the coast of Honshu, Japan, 22 km (14 mi) east of the Izu Peninsula and 36 km (22 mi) southwest of Bōsō Peninsula. As with the other islands in the Izu Island group, Izu Ōshima forms part of the Fuji-Hakone-Izu National Park. Izu Ōshima, at 91.06 km² is the largest and closest of Tokyo's outlying islands, which also include the Ogasawara Islands.

Kōzushima, Tokyo

Kōzushima Village (神津島村, Kōzushima-mura) is a village located in Ōshima Subprefecture, Tokyo Metropolis, Japan. As of 1 June 2016, the village had an estimated population of 1,856, and a population density of 99.9 persons per km². Its total area is 18.58 square kilometres (7.17 sq mi).

Mikurajima, Tokyo

Mikurajima Village (御蔵島村, Mikurajima-mura) is a village located in Miyake Subprefecture, Tokyo Metropolis, Japan. As of 1 June 2016, the village had an estimated population of 328, and a population density of 16 persons per km². Its total area is 20.54 square kilometres (7.93 sq mi).


Miyake-jima (三宅島, "Miyake Island") is an inhabited volcanic island in the Izu archipelago in the Philippine Sea approximately 180 kilometres (110 mi) southeast of Honshu, Japan. As with the other islands in the Izu Island group, Miyake-jima forms part of the Fuji-Hakone-Izu National Park.

Miyake Subprefecture

Miyake Subprefecture (三宅支庁, Miyake-shichō) is a subprefecture of Tokyo Metropolis, Japan. The organization belongs to the Tokyo Metropolitan Government Bureau Of General Affairs.

It includes the following villages on the Izu Islands:

Miyake (village on Miyakejima)

Mikurajima (village on Mikurajima)Its area is 76.08 square km and 3184 people.

Because of the eruptions of the main volcano, Miyakejima was completely evacuated from September 2000. After a four-year period of volcanic emissions, residents were allowed to return permanently on February 1, 2005.

Miyakejima Airport

Miyakejima Airport (三宅島空港, Miyakejima Kūkō) (IATA: MYE, ICAO: RJTQ) is an airport located 19 km (12 mi) east of Miyake village on the island of Miyakejima in the Miyake Subprefecture Tokyo, Japan.

In the past, flights from Haneda Airport were suspended as the area contained high sulfuric gas concentration from the July 14, 2000 volcanic eruption. Flights have resumed during April 2008, after sulfuric gases in the air have dropped to levels below 0.2ppm. There is also a helicopter that arrives via Izu Ōshima.


Nii-jima (新島) is a volcanic Japanese island administered by Tokyo Metropolitan Government. It is one of the Izu Seven Islands group of the seven northern islands of the Izu archipelago, and is located approximately 163 kilometres (101 mi) south of Tōkyō and 36 kilometres (22 mi) south of Shimoda Shizuoka Prefecture. The island is the larger inhabited component of the village of Niijima Village, Ōshima Subprefecture of Tokyo Metropolis, which also contains the larger, neighboring island of Shikine-jima and the smaller, uninhabited Jinai-tō. Nii-jima is also within the boundaries of the Fuji-Hakone-Izu National Park.

On the southern tip of Nii-jima, there was formerly a launch site for experimental and sounding rockets.

Niijima, Tokyo

Niijima (新島村, Niijima-mura) is a village located in Ōshima Subprefecture, Tokyo Metropolis, Japan. As of 1 June 2016, the village had an estimated population of 2,697, and a population density of 97.9 persons per km². Its total area is 27.54 square kilometres (10.63 sq mi).

Niijima Airport

Niijima Airport (新島空港, Niijima Kūkō) (ICAO: RJAN) is a public aerodrome located 1.5 NM (2.8 km; 1.7 mi) southeast of the village of Niijima, on the island of Niijima, one of the Izu Islands in the Philippine Sea, south of the Izu Peninsula, Japan. Niijima Village is part of Greater Metropolitan Tokyo, and the airport is operated by the Tokyo Municipal Government.

To-shima, Tokyo

Toshima (利島村, Toshima-mura) is a village located in Ōshima Subprefecture, Tokyo Metropolis, Japan. The village comprises the whole of To-shima Island.

The island, at 4.12 square kilometres (1.59 square miles), is one of the smallest inhabited islands in the Izu Island chain. Approximately 330 people live on the island. Eighty per cent of the island is covered by camellia forests. From November to March, much of the island is red from the camellia flowers. The island is also home to the Saku lily, the largest lily in the world.

The island is between Izu Ōshima, the largest of the Izu Islands, and Nii-jima. Ferries that sail to Nii-jima make a brief stop in To-shima. Toshima is also accessible (weather permitting) by helicopter departing from Ōshima island, from Ōshima airport it is a 10-minute flight to To-shima.

The main industry on To-shima is fishing. There is some small-scale farming and tourism.

Tori-shima (Izu Islands)

Tori-shima (鳥島, Tori-shima or Izu-no-Tori-shima), literally meaning "Bird Island", is an uninhabited Japanese island in the Pacific Ocean. The volcanic island is part of the Izu Islands.

Ōshima Subprefecture (Tokyo)

Ōshima Subprefecture (大島支庁, Ōshima-shichō) is a subprefecture of Tokyo Metropolis, Japan. The organization belong to Tokyo Metropolitan Government Bureau Of General Affairs.

It includes the following towns and villages on the Izu Islands:

Ōshima (town on Izu Ōshima)

Toshima (village on Toshima)

Niijima (village on Niijima and Shikinejima)

Kōzushima (village on Kōzushima)It covers 141.82 square km and 13,825 people.

Special Wards
of Tokyo
(Tama area)


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