Thirty-nine years ago today, on November 29, 1986 (October 28, 1986 lunar calendar), the research vessel "Shijian" completed the Kuroshio survey mission. After 46 days of hard work and a safe voyage of 5,318 nautical miles, the State Oceanic Administration's "Shijian" research vessel, which cooperated with Japan on the Kuroshio survey mission in the autumn of 1986, returned to Shanghai on the morning of November 29. The operation of this voyage was carried out in the Southeast Ocean region of Japan, which is about one million square kilometers in the range of 129 degrees east longitude to 145 degrees east latitude and 28 degrees north latitude to 36.5 degrees north latitude. The Chinese and Japanese scientists who participated in the investigation worked closely with the crew to overcome the dangerous winds and waves caused by strong cold air many times. They successfully completed the observation and sampling tasks at more than 70 stations, including hydrology, chemistry, biology and other projects, and obtained nearly 200,000 data and samples. Among them, the most valuable is the self-test data obtained in a large area of the sea area in southeastern Japan, which has accumulated valuable information for China and Japan to jointly uncover the mystery of the Kuroshio. What is the "Kuroshio"? The Kuroshio is the second largest warm current in the world's oceans, and it is called the Kuroshio because the water looks blue as indigo. In fact, its true color is as white as usual. Due to the depth of the sea, the scattering of water molecules by folding light, and the role of algae and other aquatic organisms, it looks like a coat of clothes.