Fig. 1: The overview of the marine environment in the north South China Sea.

The contour line of −134 m indicates the coastline in the LGM lowstand. It is noted that no water from the SCS has gone through the Taiwan Strait during the LGM lowstand. The black rectangle indicates the area of Fig. 2a. The thick red line shows the main stream and an intruded looping of Kuroshio Current19. The thick blue line shows the pathway of the Intermediate Water Circulation, modified from past studies21,22,23,24,25. The ADCP data in this study (heave blue arrow in the black rectangle). KC Kuroshio Current, IWC Intermediate Water Circulation, MT Manila Trench, RT Ryukyu Trench.