is a river in

Hokkaidō is Japan's second largest island and comprises the largest and northernmost prefecture, making up its own region. The Tsugaru Strait separates Hokkaidō from Honshu; the two islands are connected by the undersea railway Seikan Tunnel. The la ...

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

. The Rumoi is in length. It traces its source to

Mount Poroshiri or sometimes Mount Horoshiri is located in the Hidaka Mountains, Hokkaidō, Japan. Its name was derived from a phonetic kanji transcription of the Ainu words for "great mountain", ''poro-shiri''. It is the highest mountain in the Hidaka ran ...

in the Hidaka Mountain range, and flows across

Rumoi Subprefecture is a subprefecture of Hokkaido Prefecture, Japan. As of 2011, it had a population of 52,627 and an area of . The population density of the subprefecture, 13 people per km2, is very low compared to the rest of Japan. The population of Rumoi Subpr ...

in the west of

and empties into the

Sea of Japan The Sea of Japan is the marginal sea between the Japanese archipelago, Sakhalin, the Korean Peninsula, and the mainland of the Russian Far East. The Japanese archipelago separates the sea from the Pacific Ocean. Like the Mediterranean Sea, it h ...

. The

mouth In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on ...

of the Rumoi River is in the city of Rumoi.

References

Rivers of Hokkaido Rivers of Japan {{Japan-river-stub