<P> The hydrological isolation of the Sea of Japan also results in slightly lower average water salinity (34.09 ‰, where ‰ means parts per thousand) compared with the Pacific Ocean . In winter, the highest salinity at 34.5 ‰ is observed in the south where evaporation dominates over precipitation . It is the lowest at 33.8 ‰ in the south - east and south - west because of frequent rains and remains at about 34.09 ‰ in most other parts . </P> <P> Thawing of ice in spring reduces water salinity in the north, but it remains high at 34.60--34.70 ‰ in the south, partly because of the inflow of salty water through the Korea Strait . A typical variation of salinity across the sea in summer is 31.5 ‰ to 34.5 ‰ from north to south . The depth distribution of salinity is relatively constant . The surface layer tends to be more fresh in the sea parts which experience ice melting and rains . The average water density is 1.0270 g / m (0.0017311 lb / cu yd) in the north and 1.0255 g / m (0.0017285 lb / cu yd) in the south in winter . It lowers in summer to 1.0253 and 1.0215 g / m (0.0017282 and 0.0017218 lb / cu yd), respectively . </P> <P> Few rivers flow into the Sea of Japan from mainland Asia, the largest being Tumen, Rudnaya, Samarga, Partizanskaya and Tumnin; all of them have mountainous character . In contrast, numerous large rivers flow from Honshū and Hokkaidō into the sea, including Japan's four largest rivers in the Shinano, Ishikari, Agano and Mogami . The total annual river discharge into the sea is 210 km (50 cu mi) and is relatively constant through the year, except for a minor increase in July . Most water (97% or 52,200 km (12,500 cu mi)) flows into the sea through the Korea Strait and discharges through the Tsugaru (64% or 34,610 km (8,300 cu mi), La Pérouse 10,380 km (2,490 cu mi)) and Korea straits . Rainfall, evaporation and riverine inflow make only 1% of the water balance . Between October and April, the outflow exceeds the inflow due to the lower income through the Korea Strait; this balance reverses between May and September . </P> <P> The sea has complex tides, which are induced by the tidal wave of the Pacific Ocean penetrating through the Korea Strait and Tsugaru strait . The tides are semi-diurnal (rise twice a day) in the Korea Strait and in the northern part of the Strait of Tartary . They are diurnal at the eastern shore of Korea, Russian Far East and the Japanese islands of Honshū and Hokkaidō . Mixed tides occur in Peter the Great Gulf and Korea strait . The tidal waves have a speed of 10--25 cm / s (3.9--9.8 in / s) in the open sea . They accelerate in the Korea Strait (40--60 cm / s or 16--24 in / s), La Pérouse Strait (50--100 cm / s or 20--39 in / s) and especially in the Tsugaru Strait (100--200 cm / s or 39--79 in / s). </P>

Which body of water lies between china and japan