Several near-surface currents flow in the Korean littoral sea. These include the Tsushima Warm Current, the Korean Donghan Current, the Yellow Sea Warm Current, the North Korea Cold Current, and the Yellow Sea Coastal Compensation Current. On a broader scale, the Korean littoral sea is strongly influenced by the Kuroshio Current that flows northward along the east coast of the Asian continent, from the Pacific east of the Philippines. The Kuroshio is one of the world's strongest surface ocean currents. Another current bifurcates north of Okinawa Island, with the northern branch divided again into the Tsushima Warm Current and Yellow Sea Current.

The Tsushima Warm Current again divides into two branches before entering the East Sea. One branch flows northward along the western coast of the Japanese islands. Another branch flows into the warm East Korean Current along the east coast of Korea. The warm East Korean Current strengthens in summer and weakens in winter. At its maximum strength, it influences the coastal waters of Hamgyeongbuk-do.

The Tsushima Warm Current, which runs northward along the continental shelf of the East China Sea, crosses the open sea, flowing 50 to 60 nautical miles west of the Koto Islands between Jeju and Koto. From there it bifurcates into the east and west branches. The western current flows north-northeastward and enters the East Sea near Seo Sudo, where it again runs northward along the East Sea. The eastern current flows toward the open sea of Gawajiri Headland via Dong Sudo . Flow velocity near its streamline axis is 30-40 ㎝/s at the surface east of Jejudo, with increasing velocity as it approaches Tsushima Island. The velocity reaches 50 ㎝/s by the total depth near Seo Sudo. The surface layer current, which flows from eastward to northeastward at a mean speed of 0.5-1.0 knots, is strongest near the surface near Seo Sudo and Dong Sudo. Summer velocities are faster and winter velocities are slower than these averages.

A branch of the Liman Current flowing southward from Okhotsk Sea forms the North Korea Cold Current along the coast of Hamgyeongbuk-do and Hamgyeongnam-do. This current strengthens in the winter and influences southern Gangwon-do. In summer, as the water temperatures rise, warm-water fish, such as sauries, anchovies, amberjacks, mackerels, scombroids, and cuttlefish, accumulate in the East Sea. These fish migrate northward along warm water between spring and summer, and move southward in autumn as the water temperature falls. The Alaska Pollack is a typical fish that inhabits cold water, and ordinarily moves near the coast of Sokcho.

The Yellow Sea Current, which flows northward west of Jeju, is relatively weak. It tends to flow into Bohai Bay in summer, but weakens in winter because of the influence of northwesterly winds. Cold currents cannot exist in the Yellow Sea because it is closed by land on its northern edge. The littoral current, which flows southward along the west coast of Korea, reaches its peak intensity in winter because of the influence of northwesterly winds. Yellow corvinas, saurels, brown croakers, anchovies, mackerels, and other fish inhabit the relatively warm waters of the Yellow Sea. Abundant nutritious salts exist in the Yellow Sea because large rivers flow into it from Korea and China. The fry of fishes born in the Yellow Sea spend their developmental period there and move southward in autumn. The South Sea has a high water temperature year-round because of the influence of the Kuroshio Current and has abundant fish, seaweed, and shellfish.