China Is Mapping the Ocean as It Prepares for Submarine Warfare With US

Some of the surveying is for mineral deposits and fishing grounds, but the data the ships collect has a military application. 

It gives Beijing a detailed picture of the maritime environment in which



submarine battles will be waged if conflict erupts, naval experts say. 

China is conducting a vast undersea mapping and monitoring operation across the Pacific, Indian and Arctic oceans, building detailed knowledge of marine conditions that naval experts say would be crucial for waging submarine warfare against the United States and its allies.