This is a children's literature on the theme of marine scientific research. Through a warm letter from home and a special letter, it aggregates into a unique portrait of China's marine strategy. From polar research to deep-sea exploration at 10,000 metres, the work presents the brilliant achievements of China's marine science and technology in a large span of time and space. The sea adventures of China's first oceanographic survey vessel Dongfanghong, the Antarctic rescue of the polar icebreaker Xuelong, the silent guardianship of the space survey vessel Yuanwang, and the frightening moment when a manned deep dive was attacked by a black chimney at the bottom of the sea. ...... A richly detailed story of scientific research brings together the iterations of the great national weapon of marine scientific research, the generations of Chinese marine scientists The story is a vibrant representation of the geological and life wonders of the sea, including cold springs and hydrothermal fluids.