This photo taken on March 25, 2025 shows the construction site of the Shantou Bay undersea tunnel in Shantou City, south China's Guangdong Province. The Shantou Bay undersea tunnel, the world's first single-hole double-track undersea tunnel with a designed speed of 350 km per hour, was broken through on Wednesday. The 9,781-meter-long tunnel is a project of the Shantou-Shanwei high-speed railway. (Xinhua/Liu Dawei)