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Islands Connecting People and the Land. Oki Islands UNESCO Global Geopark

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The Continental Age

No. Site Name Location Outline Board or Photo
Ⅰ-3 Oki Gneiss, Choshi Dam Dogo Oki Gneiss provides us with evidence of Oki's continental origin. Rocks of the same composition formed in the same period are also found in the Hokuriku Region of Japan, and on the Eurasian Continent. Board

The Formation of the Sea of Japan

No. Site Name Location Outline Board or Photo
Ⅱ-1 Accretionary Lapilli and Lake Sediments, Jodogaura Coast Dogo Jodogaura Coast has been selected as a place of National Scenic Beauty and is one of the most iconic sightseeing locations of the island. Here you can observe rocks from volcanic eruptions that occurred 26 million years ago on the Eurasian Continent, and lacustrine sediment that was deposited in a large lake on the continent 26 million years ago. Board
Ⅱ-4 Quarry Site, Koji Dogo Here you can observe lacustrine sediments that formed in a lake on the Eurasian Continent 20 million years ago. This rock, called Goka Rock, is easily manufactured and was often used as paving stones. Board
Ⅱ-6 Banded Lacustrine Sediments Dogo You can see many different layers in this rock which was formed in a lake 20 million years ago. The striped pattern records the sedimentation of organic matter and minerals that were deposited at the bottom of the lake over time. Board
Ⅱ-12 Fossil Site, Utagi Dogo Here in Utagi you can observe fossils of sea creatures that lived around 16 to 10 million years ago when the land of Oki was at the bottom of the Sea of Japan. Board
Ⅱ-13 Diatomite, Shionohama Beach Dogo At Shiohama Beach, you can see a rock called diatomite. Diatomite is a soft rock composed of the fossilized remains of diatoms (phytoplankton) that were deposited on the sea floor. This rock was formed 16 to 10 million years ago, telling us that the land of Oki was at the bottom of the sea at this time. Diatomite is an ideal material for fire resistance and insulation, and is also used for wall material and charcoal grills. Board

The Volcanic Island Era

No. Site Name Location Outline Board or Photo
Ⅲ-1 Quartz Syenite & Hornfels, Oyama Nishinoshima This rock was formed by the underground movement of magma around seven million years ago, just before volcanic eruptions commenced. You can also see rocks that were burnt by the heat of the magma in the area. Board
Ⅲ-4 Mt. Takuhi (Central Pyroclastic Cone & Takuhi Shrine) Nishinoshima Mt. Takuhi is the highest peak of the Dozen Islands, and a former volcano that erupted within the Dozen Caldera in the middle period of the volcanic activity of the Dozen Islands. Located half way up the mountain is the Takuhi Shrine, which enshrines a deity long believed to protect those out at sea. The relationship between this shrine and naval protection may be because the shrine's watch fire had a function similar to a lighthouse, providing a signal of safety to boats at night long ago. Board
Ⅲ-5 Dozen Caldera seen from Onimai Lookout Nishinoshima Onimai Lookout is located in the southwest of Nishinoshima Island, and is the outer rim of the Dozen Caldera. Looking out at the sea from this point, you can compare the rough Sea of Japan to the calm waters of the Inner Sea. You can still see the remains of stone walls that marked out the farm land for Makihata, a unique method of crop rotation farming that was developed on the islands. These walls are called aigaki. Today, horses and cows roam freely around the mountain. Board
Ⅲ-8 Dozen Caldera seen from the Kirogasaki Lighthouse Ama Kirogasaki Lighthouse is located at the southernmost point of Nishinoshima Island and boasts a sweeping view of the entire Dozen Caldera. The sea on the south side of the lookout is the widest of the three channels that connect the inner sea to the Sea of Japan, and is called Okuchi, which means 'large mouth'. Board
Ⅲ-9 Scoria Cone, Akiya Coast Ama The red rock that composes the cliff is called scoria, and was formed by layer upon layer of lava that spurted out of the volcano. You can also observe volcanic bombs inside the bright red rocks along the coast.
The lava that flowed out of the volcano in this area is believed to have created the lowland area of Nakanoshima Island.
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Ⅲ-10 Ichnofossils, Shimazushima Island Chibu Here you can find ichnofossils (fossils of the biological activities of organisms) of burrows dug into the sand at the bottom of the sea. Board
Ⅲ-11 Sekiheki Pyroclastic Cone (From Lookout) Chibu Sekiheki is the cross-section of a former volcano. The rock is a bright red color because the lava was ejected from the volcano at a very high temperature, causing the iron content in the lava to oxidize as it contacted the air. Board
Ⅲ-13 Dozen Caldera seen from Mt. Akahage Chibu There are no trees growing around Mt. Akahage which gives us an unobstructed 360 degree view of the Dozen Caldera: Mt. Takuhi in the center (central pyroclastic cone), Nishinoshima Island, and Nakanoshima Island (outer rim of the caldera). Board
Ⅲ-14 Ichnofossils, Tsuma Dogo The biological movements of life that lived around six million years ago in the shallow sea can be observed here in these ichnofossils on the edge of the road. Board
Ⅲ-17 Three Rock Types of the Shirashima Coast Dogo The Shirashima Coast has been designated a National Place of Scenic Beauty and is one of the most famous site seeing spots in Oki. You can also see three different kinds of igneous rock on the coast, rhyolite, trachyte and basalt, and observe their different features. Board
Ⅲ-20 Feeder Dike, Shiro Coast Dogo The funnel-shaped rock you can see here is a feeder dike, which is a magma pathway through which magma erupted 5.5 million years ago. The magma that passed through the dike cooled and hardened mid-ascent, leaving it in its present shape. The lava that erupted from this dike formed the peaks of the mountains to the north and south. Board
Ⅲ-22 Rhyolite, Okutsudo Coast Dogo The Japanese word for rhyolite is 'ryuumongan' which roughly translated means 'flowing form rock'. This name reflects the appearance of the rock, which often has a flow-like pattern. You can observe this pattern in these rhyolite cliffs that were formed 5.5 million years ago.
However, contrary to its name, rhyolitic lava is highly viscous and does not flow easily. Instead, the swirling, flow-like pattern is created by the components of this thick lava which become stretched and do not blend.
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Ⅲ-25 Obsidian and Volcanic Vent, Kishihama Dogo Buried within the pyroclastic rock on the former magma path here are the volcanic glasses obsidian, perlite and pitchstone. These rocks were formed by magma which cooled very rapidly. Photo
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Ⅲ-33 Tokage-iwa seen from the Lookout Dogo When seen from a distance, this strangely-shaped rock resembles a lizard scaling the cliff. While the shape of the rock is interesting, the geological composition of the rock, Anorthoclase Phonolitic Trachyte, is also unusual. There are only a few places in the world where it is found in such a large size. Board
Ⅲ-40 Kuboro Beach Mantle Xenoliths Dogo There are various rocks to be seen on the Kuboro Coast. Among them are mantle xenoliths, which are rocks that contain fragments of the earth's mantle that were carried up from many kilometers deep under the ground during volcanic activity. These mantle xeoliths allow us to see deeper into the mantle than we are able to dig. Board
Ⅲ-41b Kuroshima Island Mantle Xenoliths Dogo This tiny island offshore of Oku is a former volcanic crater that erupted 3.5 million years ago. The entire island is composed of vertical column-shaped rocks called columnar joints. These columnar joints were formed due to the way that the basaltic lava cools rapidly, causing the rock to crack systematically, forming columns. Mantle xenoliths are also found on this island. Board
Ⅲ-43 Columnar Joints and Samizu-no-taki, Ganya Dogo In this area there are hexagonal and pentagonal shaped rocks that fell from the cliff above. These shape of these rocks was formed due to the difference in temperature between the outside and inside of the lava when it cooled and hardened. Board
Ⅲ-47 Misaki Basalt Explosion Crater Dogo The Oki Airport in Misaki is situated on a wide plain that was created by lava flow five million years ago. The flat land was the result of lava that flowed smoothly out of the volcano.
The steep cliff face in front of the Saigo-misaki Lighthouse features a volcanic crater which is only half remaining, giving the appearance of a giant bowl cut in half.
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Ⅲ-49 Basalt, Uzuki Coast Dogo At the Uzuki Coast you can find the most recent lava in Oki that erupted 400 thousand years ago. You can see lava that hardened in two different ways. Much of the coast is formed by lava that cooled and hardened as it flowed out of the volcano, creating round boulders that appear to be piled on top of each other. On the other hand, columnar joints that were formed by lava that cooled as it stopped flowing can be seen on a hill which has a small shrine built on it.
Another interesting thing you can see here is the subalpine plant shirouma-asatsuki growing right on the coast.
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From Peninsula to Islands

No. Site Name Location Outline Board or Photo
ⅣG-1 Matengai Cliff, Kuniga Coast Nishinoshima This 257m high eroded cliff is the one of the most spectacular sea cliffs in Japan. It was carved by erosion from the strong winter winds and waves. If you look closely at the cliff, you can observe layer upon layer of ash colored rock and dark red colored rock, which is the result of the repetitive volcanic eruptions that created the land. Board
ⅣG-2 Tsutenkyo Arch (Bridge to Heaven), Kuniga Coast Nishinoshima This sea arch was shaped natural by erosion from the rough waves of the Sea of Japan. It was formerly the entrance to a sea cavern, but landslides caused the back of the cavern to collapse and crumble away. Board
ⅣG-3 Kuniga Coast seen from Akao Lookout Nishinoshima The Akao Lookout boasts a fantastic view of the Kuniga Coast. The impressive Kuniga Coastline has been shaped by erosion from the waves of the Sea of Japan, and the strong winds from the continent. Board
ⅣG-7 Tengawa-no-mizu (Water of the Heavenly River Spring), Hobomi Ama This spring is said to have been named in the Nara Period (710 - 794) by the famous buddhist priest Gyoki. It is designated one of the Top 100 Exquisite and Well-Conserved Waters of Shimane and has never dried up. It produces an impressive 400 tonnes of water daily. In the past it was used as a private water supply system, although today it is used for agriculture. Photo
ⅣG-8 Natural Springs of Mt. Kinkouji Ama There isa natural spring located at the peak of Mt. Kinko-ji. The reason for this is unknown, however Mt. Akahage in Chiburijima Island, and Onimai in Nishinoshima Island also have springs at the peak. The water supplies the cows and horses on the mountains with plentiful drinking water. Board
ⅣG-9 Kawai Springs Chibu Right beside the road in Kawai you will find the Kawai Springs. The people of the island have utilised this water since long ago, and the springs have been designated one of the Top 100 Exquisite and Well-Conserved Waters of Shimane Prefecture. Board
ⅣG-11b Rosoku-jima and Uma-nose-jima Dogo From this place you can see the famous Rosoku-iwa (Candle Island). On sightseeing boats in the area you can see the candle become lit when the setting sun comes into alignment with the island. Rosoku-iwa is a stack, which is land that has become isolated by processes of erosion. Nearby you can also see Uma-nose-jima (Horseback Island) and other strangely-shaped rocks. Board
ⅣG-13 Yui Pond Dogo This perfectly circular pond is around 250m in diameter and a thriving ecosystem. It is often visited for environmental workshops and eco tours. In the past there were many theories about how the pond formed, such as where a meteorite crashed or volcanic crater, however a recent study discovered that the pond was created by a large-scale landslide from the surrounding cliffs. A depression then formed in the center and filled with water, eventually creating the Yui Pond. Board
ⅣG-15 Byobu-iwa (Folding Screen Rock), Mt. Washigamine Dogo This beautiful formation of columnar joints resembles a folding screen and was named accordingly. The surrounding area is a cauldron that was formed by a large depression created by volcanic activity and then filled by subsequent eruptions five million years ago. Board
ⅣG-18 Yui-mae-no-su (Yui Inter-tidal Shore Platform) Dogo The fishing port of Yui features the widest wave-cut bench in Dogo Island, called Yui-mae-no-su (Yui Inter-tidal Shore Platform). It was formed by lacustrine rock dated at 20 million years ago that continues to be eroded by the wind and waves of the sea. Board

Ecosystem

No. Site Name Location Outline Board or Photo
ⅣB-2 Vegetation of the Shirashima Coast Dogo At the Shirashima Lookout you can observe an interesting distribution of plants that is peculiar to the Oki Islands. Here there are northern, southern as well as continental species of plants in the same environment. Also, though they normally begin to wilt in July, you can see the hydrangeas along the walking trail in bloom until November.
This is thought to be due to the effect of the Tsushima Warm Current and the cold wind from the Eurasian Continent which creates a warm and humid environment all year round.
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ⅣB-3 Katakuri (Dogtooth Violet) Park, Ozuku Dogo Though this flower is a subalpine species, in Oki it can be found right on the coast. In the past the flower was becoming threatened due to over picking, however thanks to the efforts of volunteers in the area to conserve them you can see them growing abundantly this park. Photo
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ⅣB-7 Oki Salamander, Nakadani Dogo The Oki Salamander is a unique species only found in Dogo Island. The species has attracted attention as it evolved in a short period of time, shedding light on the evolutionary process. However, in 2005 the Oki Salamander was added to the Alliance for Zero Extinction list of highly threated species. The organisation has listed 790 species and 595 places in the world that are the 'last habitat' of an endangered species. Board
ⅣB-9 Kabura-sugi Japanese Cedar Dogo This peculiar tree separates into six trunks at a height of about 1.5 meters. It was originally several Japanese cedar trees that joined together and began to grow this way. The tree is named kabura-sugi because it is thought to resemble a kabura-ya, a whistling arrow that was used to in rituals and to signify the outbreak of war. Photo
ⅣB-11 O-iwa-kagami, Okutsudo Dogo Although the Okutsudo Coast is zero meters above sea level, along the nature trail you can see the subalpine plant O-iwa-kagami (Schizocodon soldanelloides). There are other strange plants here including the montane variety Mizunara oak (Quercus crispula), the northern plant Itaya-kaede Mono Maple, the southern plant Tobera (Pittosporum tobira), and the continental plant Daruma-giku (Aster spathulifolius). Board
ⅣB-12 Subalpine Plants, Matsushima Island Dogo On Matsushima Island which you can see from this point, there are many subalpine Kurobe (Thuja standishii) and O-iwa-kagami (Schizocodon soldanelloides) growing. The reason that subalpine plants are found here at zero meters above sea level is unclear, however it is thought that they escaped to Oki during the last glacial period when Oki became connected to the mainland, and adapted to the environment after they became isolated on the islands when the sea level rose again. Board
ⅣB-14 Vegetation of the Shizen-kaiki-no-mori Forest Dogo The Shizen-kaiki-no-mori Forest is protected under Okinoshima Town legislation. A forest of Japanese cedar trees of this size is uncommon all over Japan, and is very precious. The area is also the habitat of endemic species such as the Oki Rhododendron, and is a popular hiking area. Board
ⅣB-15 Chichi-sugi and Wind Holes Dogo The Chichi-sugi Japanese cedar tree has 24 new roots that you can see growing downwards from the tree's many trunks. The tree's name chi-chi, meaning breasts, comes from it's strange shape and drooping roots. The reason for this shape is that the tree is situated on rocky ground with very little topsoil, which means the tree is unable to absorb much moisture from the ground.

Instead the tree's dangling roots are used to absorb moisture from the highly humid environment.
The ground around Chichi-sugi is formed by rocks that have fallen down from the peak of Mt. Daimanji. Cold air flows between the gaps between these rocks, called wind holes, and collides with the surrounding warm air, creating a humid environment. This is why we can see many plants that usually prefer waterside and wetlands environments here, such as Japanese Judas Tree (Cercidiphyllum japonicum) and Japanese wing nut (Pterocarya rhoifolia).
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ⅣB-16 Vegetation of the Kumi Coast Dogo Around these beautiful white rhyolite cliffs on the coast we can see the endemic Oki-no-abura-giku chrysanthemum as well as the continental Daruma-giku chrysanthemum, the southern plant Sharinbai (Rhaphiolepis indica var. umbellata) and a remnant plant from the glacial age called Shirouma-asatsuki (Allium shoenoprasum var.orientale). You can also observe the volcanic glass obsidian here. Board

Lifestyle

No. Site Name Location Outline Board or Photo
ⅣF-1 Makihata Stone Walls, Onimai Nishinoshima Makihata is a unique crop rotation farming method that was developed on the Oki Islands. Makihata crops were separated into four fields of grain and cattle and rotated. The method was devised as a solution to the meagre soil and limited flat land on the islands, and use the land effectively. At Onimai you can see the remnants of the stone walls that were used to demarcate the fields. Photo
ⅣF-2 Funabiki Canal, Funakoshi Nishinoshima This canal cuts through the center of Nishinoshima Island, joining the inner sea and the Sea of Japan. Before the canal was made in 1915, the boats had to be laboriously transported overland in order to reach the Sea of Japan from the Inner Sea. The name of the surrounding town, Funakoshi (boat crossing) is said to have been named after this practice. Photo
ⅣF-4 Funagoya Traditional Boathouses, Tsuma Dogo These quaint boathouses unique to this fishing village, are shelters built to protect the fishing boats from weathering. They were made using traditional materials and technique. They were also built on a slope on the beach directly connected to the sea. They can stay in this position all year due to the small tidal fluctuation of the Sea of Japan. Board
ⅣF-5 Port of Call, Saigo Port Dogo The Saigo Bay is a natural port with a narrow entrance and wide inner sea. This port was a port of call for trading ships following the Kita-mae-bune (Northern Bound Ships) Trading Route, which revolutionized trade in Japan in the 17th century. As a result of this role in the prosperous trade route, the islands became much more developed that one might expect as isolated islands. This was noted in the diary of Lafcadio Hearn (Koizumu Yakumo), the Irish-American author who lived and travelled in Japan and is credited with popularizing many traditional Japanese stories abroad. Photo
ⅣF-6 Misaki Lava Plateau and the Oki Airport Dogo This flat expanse in Misaki is the location of the Oki Airport, and was created by lava flow from volcanic activity 500 thousand years ago. The lava flowed smoothly from the volcano creating a wide flat space.
In the steep cliff below the Saigo-misaki Lighthouse is a volcanic crater that looks like a giant bowl cut in half. This was the site of a phreatic eruption (an eruption of steam).
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ⅣF-8 Tamawakasu-mikoto Shrine Dogo The Tamawakasu Shrine is the main general shrine of Oki. Every year on 5th June during the Gorei-furyu Festival, one of the three big festivals on Dogo Island, a miraculous event takes place where eight sacred horses carrying the gods from eight areas gallop to the shrine to pay their respects. The giant tree on the grounds of the shrine is called Yao-sugi and is over 1000 years old. Photo
ⅣF-9 Oyama Shrine, Fuse Dogo The Oyama Shrine in Fuse is an ancient form of shrine that has no shrine building. Instead the giant Japanese cedar tree here, Chichi-sugi, is the shrine where a deity resides. You can see the shrine entrance, called tori, in front of the tree. During the Yama-matsuri Festival that occurs here biannually on the first Sunday of April, participants must tie a hardy vine around the tree seven and a half times. It is said to be one of the most ancient mountain festivals in Japan. Photo
ⅣF-11 Fukuura Tunnel Dogo The Fukuura Tunnels are a set of tunnels that were dug in the soft rock of pyroclastic flow. The smaller of these tunnels was dug by hand around 1870. The larger tunnel was first dug by hand and dynamite, and then widened using heavy machinery. These tunnels show the development of transport over the ages (from on-foot, to horse and cart, to automobiles), and the development of civil engineering technology. For this reason they have been designated as sites of Public Works Heritage by the Japan Society of Civil Engineers. Board
ⅣF-13 Yui River Landslide Disaster Site Dogo A record downpour occurred in August 2007 (maximum rainfall 131mm per hour) that resulted in flooding and a large landslide in the Yui Area. The road alongside the river was swept away as were many of the foundations of houses alongside the river. The area was repaired and the river was widened and the location of the bridge changed to prevent another disaster in the future. Also, the following year a disaster relief group was formed and a hazard map was made with the help of the people in the area. Board
ⅣF-15 Dangyo-no-taki Waterfall Dogo There is a large and a small waterfall here.
The water has spiritual significance and has been designated as one of the Top 100 Exquisite and Well-Conserved Waters of Shimane by the Ministry of the Environment.
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ⅣF-16 Makihata Stone Walls, Mt. Akahage Chibu The stone walls you can still see here today are the remains of a unique four-field farming method developed on the islands, called Makihata. Makihata was devised to compensate for the meagre soil and limited flat land on the islands, and use the land effectively. Board
Miyao Remains Dogo Relics from the Jomon Period (14,000 BC – 300 BC) have been discovered around the coastal areas of Dogo Island. These artifacts include earthenware, stone tools and many objects made from obsidian excavated in Kumi, in the northwest of Dogo Island.
Today you cannot see the excavation sites, however the artifacts are being held by the Board of Education.

Museum, etc.

No. Site Name Location Outline Board or Photo
Saigo Port Dogo This port is the main port of Dogo Island. From here the Oki Kisen Ferry Company runs daily transport between the islands and to and from the mainland, Saigo Minato Port (Tottori Prefecture) and Shichirui Port (Shimane Prefecture). On level three of the port is the Oki Tourism Association which is the tourism body for all of the Oki Islands. Board
Oki Nature Museum and Geopark Center Dogo The Oki Nature Museum and Geopark Information Center is on level two of the Port Plaza Hotel which is right across the road from the ferry terminal, and can be accessed directly by the overpass from level two ofthe terminal. On the ground floor of the hotel there is the Okinoshima Town Tourism Association and a souvenir shop.
In the Nature Museum you can see special displays about the geology, insect life, birds, marine life and flora of the islands.
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Oki-ke Traditional Residence and Museum Dogo The Oki-ke Traditional Residence is located right next door to the Tamawakasu-mikoto Shrine. It is built in a traditional architectural style unique to Oki. The residence houses a museum which has a number of historical treasures on display, including the eki-rei, a station bell which was used as a mark of status from 646, and of which there are no others left in Japan. The residence and treasures have been designated Important Cultural Property of Japan. Photo
Oki Kyodo-kan Museum of Local Archaeology and Folklore Dogo Oki Kyodo-kan Museum is the old county office that was built during the Meiji Period (1868 - 1912). It is a western style building that was dismantled and rebuilt in its current location and is now a museum of local archaeology and folklore.
Outside in the garden you can see a wooden dugout canoe that was used to sail from Oki to the mainland.
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Goka Sosei-kan Museum of Local Traditional Culture Dogo At the Goka Sousei-kan you can watch short films about traditional Oki culture such as Bull Sumo and Oki Traditional Sumo. Photo
Beppu Port Nishinoshima The Oki Kisen, ferrys between the Dozen Islands, as well as sightseeing boats visiting the Kuniga Coast arrive and depart from this port.
On the second floor there is a geopark corner as well as tourism information. The Nishinoshima Town Tourism Association is located in the building next door to the port terminal.
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Furusato-kan Museum of Local History Nishinoshima The Furusato-kan Museum features artifacts such as fishing and agricultural tools as well as a collection about the flora and fauna on the islands. Photo
Kuroki-gosho Site of Residence of Emperor Godaigo and Heifu-kan Museum Nishinoshima Emperor Godaigo is believed to have spent around a year here in the Kuroki-go-sho Palace. It is now a museum dedicated to the emperor.
There is a contending story that claims the Kokubunji Temple on Dogo Island was where the emperor resided.
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Hishiura Port Ama You can catch the Oki Kisen, ferrys between the Dozen Islands, as well as the Amambo Sightseeing Boat arrive and depart from this port. On level one of the Port you can find the Ama Tourism Association, and on level two there is a geopark corner. Board
Ama Town Emperor Gotoba Museum Ama This museum features information about the exiled Emperor Gotoba, as well as artifacts and information about the island. Photo
Kuri Port Chibu You can catch the Oki Kisen, ferrys between the Dozen Islands, as well as sightseeing boats from this port. The Chibu Tourism Association and geopark corner are located inside the terminal. Board
Oki Airport Dogo Flights from to and from Izumo and Osaka (Itami) depart daily. Board

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