In Kagoshima Prefecture, the southernmost tip of Kyushu, “Kinkowan” is sandwiched between the Satsuma and Osumi peninsulas. Kinko Bay is a sea of life that reaches many urban areas, such as Kagoshima City and Kirishima City. Yet in fact, it is also a very rare place, with shallow tidal flats, and deep seas with a depth of more than 200m. Let's take a look at how this sea was born, and how you can enjoy its charm.A variety of attractions [Kinko Bay] The symbol of Kagoshima Prefecture is “Sakurajima”. Not only for tourists, but also people living in Kagoshima think this way. The active volcano floating on the ocean seems to be one reason, but did you know that it was actually “Kinkowan”? View Sakurajima Ferry

The symbol behind the Kinko Bay’s “Sakurajima” and Sakurajima Ferry. Kinko Bay and Kagoshima Bay, a sea sandwiched between two peninsulas; projecting south from Kagoshima Prefecture. Yet Kinko Bay is not just a supplement for Sakurajima. Especially since the back of Sakurajima, there are some very rare geographical features and precious nature. This attracts attention from many people, including experts. As a result of these highly praised points, the Kinko Bay’s back was added in March 2012, as part of the Kirishima Kinko Bay National Park. Kinko Bay was born from a huge eruption. Looking at the bottom of Kinko Bay from a map or satellite photo, you can see that it is generally round. Actually, the back of Kinko Bay has the same “caldera” as Aso in Kumamoto Prefecture. A huge eruption about 30,000 years ago caused the ground to collapse greatly. As a result, seawater flowed into the 20 km diameter caldera, forming the back of Kinko Bay. This terrain is called, “sea caldera” and is very rare worldwide. Caldera topography in the back of Kinko Bay

Caldera topography in the back of Kinko Bay

The inner part of Kinko Bay is a huge caldera. The caldera at the back of Kinko Bay is mostly filled with seawater, but part of the caldera topography is still left on land. Part of it is a steep cliff that follows the coastline from the north of Kagoshima City, to the back of the bay. This is near the top of the caldera wall (caldera side). At the end of Kinko Bay, off the coast of Kirishima City, three small islands called, “Hayato Santo”; which are said to be the remnants of the caldera wall that are floating.If you want to see the caldera wall with your own eyes, please visit the Tennouji Observatory in Sakurajima.

Caldera wall looking down from Yunohira Observatory. From shallow tideland, to the deep sea. One of the unusual features of Kinko Bay, is that it has both a tidal flat and access to the deep sea. It is not unusual for a tidal flat to form in the back of the bay where the waves are calm. There are also tidal flats in the back of Tokyo Bay and the Ariake Sea. However, the back of Kinko Bay is a caldera landmass. Originally, most of the coastline was a caldera wall, and there were few shallows where sediments carried by rivers and tides were deposited. However, as a result of the rivers carrying the earth and sand for tens of thousands of years, a vast tidal flat was formed in Kinko Bay. At present, the largest tidal flat in Kinko Bay is Shigetomi Higata, a 20-minute drive from Kagoshima City. The tidal flat, which covers up to 300,000 square meters (more than 6 Tokyo Domes) at low tide. Not only does it maintain the water quality and ecosystems of Kinko Bay, but it is also popular as a place of leisure.

A vast tidal flat appears at low tide On the other hand, the “depth” of Kinko Bay is a feature not seen in other bays. For example, the average depth of water in the inner bay of Tokyo Bay is 15m. On the other hand, the average water depth in the inner part of Kinko Bay is 70m; and there are some deep waters exceeding 200m deep off the coast of Kirishima City and Tarumi City. In addition, there is an active underwater volcano off the coast of Wakamiko in Kirishima City, where volcanic gases are always blowing out. The appearance of bubbles rising on the surface of the sea is called “Tagiri” among local fishermen. By the way, in the vicinity of underwater volcanoes, deep sea surveys are also being conducted by scientists about a rare creature, called “Satsuma Aorimushi”. It uses hydrogen sulfide, a volcanic gas, as an energy source. Scuba diving

Diving used for deep sea exploration. Kinko Bay is the sea of life. Kinko Bay is a “sea of life” for the Kagoshima people. For example, the “Sakurajima Ferry” operates between Kagoshima Port and Sakurajima Port in Kagoshima City, but passengers are mainly local Kagoshima citizens. It is mainly used for commuting, attending school and shopping. That's why the fare is ‪200 yen one way‬, and it's as cheap as a local bus. There are coupons and commuter passes available too. Of course, it operates 24 hours a day, 365 days a year, unless the sea is unstable due to a typhoon. Sakurajima Ferry Terminal

Sakurajima Ferry is also used as a hub for commuting. Kinko Bay has been used as a valuable fishing ground since ancient times. Aquaculture is especially popular in Kinko Bay. Yellowtail and amberjack, grown in Kinko Bay, are shipped throughout the country and are special products of Kagoshima Prefecture. In addition, it is said that a precious shrimp called, “Namikuda Beard Shrimp”, which lives in the deep sea in the tropical zone, is also rare. Kinko Bay Farm

There is a lot of aquaculture in the back of Kinko Bay.