Asō Bay

Asō Bay is a large, complex inlet that nearly cleaves the Japanese island of Tsushima in two. The bay is notable for its ria coastline, with many peninsulas and numerous small islands located close to the shore. It is part of the Iki-Tsushima Quasi-National Park. Pearls are cultured, and Japanese amberjack are farmed in its waters.
The measured COD of the bay's water was between 1 and 2,5 mg/L.

Manzeki Channel

The Manzeki Channel connects Asō Bay with Miura Bay, which opens onto the Tsushima Straits. The channel was cut by the Japanese Navy">Japan">Japanese Navy between 1895 and 1904. It was originally twenty-five metres wide and three meters deep, but was later widened to accommodate larger vessels.