The article discusses international laws regarding enforcement powers at sea, focusing on maritime zones in the South China Sea, sovereignty of coastal states, and the evolution of sea laws. It explores the principles of the law of the sea, Chinese naval power in the South China Sea, and freedom of navigation on the high seas. The research emphasizes the importance of maritime delimitation in determining legal rights and regulating human activities in the ocean. The median-line system is highlighted as a guiding principle for territorial sea delimitation.