China's coastline is hemmed in by two island chains held largely by US treaty allies. Its naval bases at Qingdao, Ningbo, Zhanjiang, and Sanya must all push through narrow, closeable straits to reach open ocean. To the south, the Malacca Strait — highlighted here — carries eighty percent of China's oil imports through a waterway less than three kilometres wide. This map shows the geographic architecture that defines and constrains Chinese sea power: the First Island Chain running from Japan through Taiwan to the Philippines, the Second Island Chain 3,900 kilometres further out at Guam, and the countries that sit across China's critical trade routes.