‘航海’ literally combines ‘航’ (háng), meaning ‘to sail’ or ‘navigation’, and ‘海’ (hǎi), meaning ‘sea’ or ‘ocean’. Together, it refers to the practice, science, or activity of navigating ships across open waters — maritime navigation. It emphasizes purposeful, skilled movement over sea routes, often involving planning, charts, instruments, and knowledge of weather and currents.

The term is commonly used in historical, professional, and educational contexts — for example, when discussing ancient explorers like Zheng He, modern shipping industries, or maritime education programs. Unlike the more general ‘坐船’ (taking a boat), ‘航海’ implies intentionality, distance, technical skill, and often long-duration voyages. It can also appear metaphorically, as in ‘航海精神’ (the spirit of maritime exploration), evoking courage and discovery.