Kuroshio that begins from the westernmost North Equatorial Current carries heat and salt to the Korean neighboring sea. Regional oceanographers know the high salinity water is originated from the Kuroshio as a form of Tsushima Current. However, how much is the Kuroshio water in the Korea Strait is not known. KIOST have been surveying from Korean waters to the tropical Northwestern Pacific once a year from 2006 as a part of POSEIDON project. There was a Kuroshio section in these surveys in June 2008 and 2010. Based on the T-S diagram, 4 water masses were identified in Kuroshio and south sea sections: East China Sea surface water, Yellow Sea bottom cold water, subtropical underwater, and North Pacific central water. Water masses were analyzed in the south sea section for these water masses. This result suggests that the high salinity water in the Korea Strait is originated from the thermocline water below the Kuroshio salinity maximum later water in June.ver, how much is the Kuroshio water in the Korea Strait is not known. KIOST have been surveying from Korean waters to the tropical Northwestern Pacific once a year from 2006 as a part of POSEIDON project. There was a Kuroshio section in these surveys in June 2008 and 2010. Based on the T-S diagram, 4 water masses were identified in Kuroshio and south sea sections: East China Sea surface water, Yellow Sea bottom cold water, subtropical underwater, and North Pacific central water. Water masses were analyzed in the south sea section for these water masses. This result suggests that the high salinity water in the Korea Strait is originated from the thermocline water below the Kuroshio salinity maximum later water in June.