Kinkowan Bay was formed
when a major volcanic eruption took place,
creating movement in the earth's crust.
Despite the fact that this is an inland bay,
the sea here reaches a remarkable depth
of 237m at its deepest point.
The bay also features Sakurajima,
one of a few active volcanoes in the world,
and a submarine volcano,
which is also active.

A national park of
volcanic landforms

Kirishima-Kinkowan National Park was formed when Kirishima-Yaku National Park was divided up into "Yakushima National Park," which is home to the area's island ecosystems, and "Kirishima-Kinkowan National Park," an area of volcanic landforms. The Aira Caldera was also added to Kirishima-Kinkowan National Park at this time.

Kirishima-Kinkowan features expanses of land and ocean that bear the mark of volcanic activity. It is home to a group of 20 volcanoes, large and small, including Mt. Sakurajima (a volcano which continues to be active to this day), and a volcano which lies under the sea. The Aira Caldera, meanwhile, is a spot of immense significance as an important reminder for the people of today about the terrible strength of the eruption that created it.

A caldera beneath the sea

Kinkowan Bay was carved out through a series of massive volcanic eruptions.

In the inner region of Kinkowan Bay lies the Aira Caldera, a hollow created when an area of land collapsed due to a massive eruption 29,000 years ago. Great masses of debris ejected by the volcano in the eruption can be seen all over Southern Kyushu, where they are given the name of "shirasu." The caldera is the site of Mt. Sakurajima, one of Japan's few active volcanoes, and of a submarine volcano in the innermost part of the bay which also continues to be active even today. At the outlet of the bay lies the even more ancient Ata Caldera, formed around 110,000 years ago.

Deep-sea fish live in the bay, which reaches a depth of 237m at its deepest point. Featuring complex formations and warmed by the "kuroshio" (a warm north-western ocean current) that flows into it, Kinkowan Bay is home to a diverse variety of organisms.

The formation of Kinkowan Bay

  1. 1

    Many millennia ago, the area currently filled by sea in the bay was instead occupied by a great volcano.

  2. 2

    Around 30,000 years ago, a massive eruption took place. Ash and lava flowed from the volcano, covering the entire area.

  3. 3

    The molten magma that was spewed out caused a cavity to open up in the ground immediately below the volcano following the eruption.

  4. 4

    Hollowed out in this way, the ground was no longer able to support the volcano's weight, and the body of the volcano itself collapsed, causing a massive caving-in of the ground.

  5. 5

    As the seawater flowed in, Mt. Sakurajima began to take shape at the southernmost point of the bay, developing into the formation we see today.


Shigetomi Beach is made up of a 53-hectare expanse of tidal flats, the largest such area in the inner Kinkowan Bay.
Connecting the sea and the land together, these tidal flats serve the role of purifying the seawater from the bay,
and are also a habitat and feeding ground for many species of wildlife.

  • Indo-pacific
    bottlenose dolphin
    Period: All Year
    Dolphins have settled in Kinkowan Bay and may be visible from the coast or from the road along Kinkowan Bay.
  • Western OspreyPeriod: All Year
    A relative of the white-bellied hawk. Ospreys fly towards the sea to catch fish.
  • Black-faced
    Period: October to May
    An endangered bird with only approx. 4,463 birds remaining worldwide (surveyed in 2019), it features a spatula-like beak.
  • Common KingfisherPeriod: All Year
    A bird with a beautiful, gem-like blue color, kingfishers can be seen around at the water's edge.
  • WhimbrelPeriod: March to May/September to November
    A rare sandpiper that stops at the tidal flats in spring and autumn. Its call sounds like a resounding, whistling voice.
  • Mamekobushi crabPeriod: March to November
    A round crab often found in tidal flats, they can walk in any direction, backwards, forwards, left, and right.
  • Fiddler crabsPeriod: April to November
    In Japanese this crab is known as the Hakusenshiomaneki, or Dancing with a White Fan to Bring In the Tide.
  • Sentinel crabPeriod: May to October
    This rare crab can only live on wide, sandy tidal flats, and is only encountered infrequently.
  • Straw wormPeriod: All Year
    Part of their nest sticks up on the tidal flats like a straw, and they spend most of their time in their nest.
  • Sea snailPeriod: March to December
    There are many snails on Shigetomi Beach, but their habitats are decreasing nationwide.


The geographical features of Kinkowan Bay are characterized by its depth,
which reaches 206m deep in the innermost part, and by its submarine volcano.

Kamitsukuri Islands 神造島

The Kamitsukuri islands is the name given to a group of three islands: Hetakojima, Bentenjima and Okikojima. They are characterized by their unusual geology, which developed when a layer of rhyolite (a volcanic rock) from the ocean floor bulged upwards and was then gradually worn away over many years.

Terayama 寺山

Terayama Observation Platform in Yoshino-cho, Kagoshima City, which stands 400m above sea level, is the perfect spot for taking in the view of the Kirishima mountain range to the north, Kinkowan Bay below and Sakurajima in front of you!!

Wakamikobana 若尊鼻

Wakamikobana is a spot directly facing Kirishima City's coastline. At the edge stands a tiny shrine, which according to legend marks the spot where Yamato Takeru (a prince who is believed to have lived in the 8th century) landed when he arrived to drive out the Kumaso, an ancient people who originally occupied this area.

Kanze (God’s Shoal) 神瀬

Kanse Lighthouse stands among the currents flowing between Sakurajima and Kagoshima City. At low tide, an expanse of sandy beach appears at the foot of this white lighthouse. Surrounded in coral reefs and seaweed beds, this area is teeming with fish.

Mt. Takatoge 高峠

Takatoge Pass is an observation platform standing at an elevation of 722m to the northeast of Tarumizu City. Visitors here can enjoy a spectacular 360-degree panoramic view around them. In spring, the slopes of the mountain are brightened with the flowers of the 100,000 wild azalea bushes that grow here.

Shinjima Island 新島

During the Anei eruption in Japan's Edo period (1603 to 1868), eruptions also occurred on the sea floor and magma raised (uplifted) the sea floor up. Many faults were also formed during the uplift.