Aso Bay

A ria bay in the center of Tsushima, Nagasaki Prefecture. It is also written as a shallow bay. The bay was formed by the subsidence of the hills that form the semi-plain in the center of Tsushima. The entrance opens toward the Korea Strait and is called Oguchi Seto. The bay is wide, covering an area of ​​240 square kilometers. The coastline is complex, with sub-bays such as Nii Aso Bay, Nobu Aso Bay, and Sumo Bay, which further give rise to sub-bays such as Saho Bay, Waita Bay, and Wada Bay, with many peninsulas and islands in between, creating a typical archipelago landscape, and it has been designated as Iki-Tsushima Quasi-National Park. The eastern side of the bay is separated from the Tsushima Strait by an isthmus, which contains the artificially incised Ofunakoshi Seto and Manzeki Seto. Since ancient times, it has been a key location for Japan against the continent, and in the old days, Sakimori (defence force) was stationed there. After the Meiji period, it became a key naval port (Takeshiki Port), from which the Combined Fleet's torpedo boats departed during the Battle of Tsushima. On Joyama (mountain) on the south coast is an ancient Korean-style mountain castle, and Asajiyama (188m, Mt. Oyama) on the east coast is a famous mountain sung about in the Manyoshu, with songs such as "Even in the drizzling rain, I could see Asajiyama of Tsushima, where a hundred boats anchor." Pearl farming is thriving within the bay, and squid fishing is also plentiful. In 1975 (Showa 50), Tsushima Airport was opened on Shireeyama (mountain) on the southeast coast.

[Yasuyoshi Ishii]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

長崎県、対馬(つしま)の中央部にあるリアス式湾入。浅海湾とも書く。対馬の中央部の準平原をなす丘陵が沈降してできた湾で、入口は朝鮮海峡に向かって開き、大口(おおぐち)瀬戸とよばれる。湾内は広く面積240平方キロメートル。海岸線は複雑で、仁位(にい)浅茅湾、濃部(のぶ)浅茅湾、洲藻(すも)浦などの支湾があり、その支湾からさらに佐保(さほ)浦、和板(わいた)浦、和田(わだ)浦などの支湾を生じ、その間に半島や島々が多く、典型的な多島海の景観を展開し、壱岐対馬国定公園に指定されている。湾の東側は、地峡部によって対馬海峡から隔てられ、地峡部には人工の切開による大船越(おおふなこし)瀬戸、万関(まんぜき)瀬戸がある。古来、大陸に対する日本の要地をなし、古くは防人(さきもり)が置かれ、明治以後、海軍の要港（竹敷港(たけしきこう)）が置かれ、日本海海戦にはここから連合艦隊の水雷艇が出撃した。南岸の城山(じょうやま)には古代の朝鮮式山城があり、東岸の浅茅山(あさじやま)（188メートル。大山岳）は『万葉集』に歌われた名山で、「百舟(ももふね)の泊(は)つる対馬の浅茅山しぐれの雨にもみたひにけり」などの歌がある。湾内では真珠養殖が盛んで、イカの漁獲も多い。1975年（昭和50）南東岸の白蓮江(しれえ)山に対馬空港が開設された。

［石井泰義］

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