As the world enters a phase of aggressive competition over untapped ocean floor resources, countries are scrambling to stake their claims. The vast economic potential on offer has made the seabed the ultimate frontier in a new Age of Exploration. China's research vessels in particular have been active in waters right across the globe. Through our exhaustive analysis of huge volumes of Chinese ship tracking data, from sand dredgers to survey vessels, we piece together a puzzle that reveals a new hidden power struggle over increasingly critical submarine resources.