China has completed excavating a tunnel beneath the Yangtze River, the country's largest waterway, marking a major milestone for a project that will connect Shanghai's Chongming Island with neighboring Jiangsu Province and expand the national high-speed rail network.

The engineering feat marks the longest continuous underwater excavation achieved by a drilling machine of its kind, state media reports.

China has completed excavating a tunnel beneath the Yangtze River, the country's largest waterway, marking a major milestone for a project that will connect Shanghai's Chongming…