The Xiamen Xiang'an undersea tunnel, the first undersea tunnel in the Chinese mainland, was completed in Xiamen, Fujian Province Thursday after four years of construction.

This tunnel is 8.695 kilometers long, and reaches a depth of 70 meters under the sea level. The life span of the tunnel is expected to be 100 years. This tunnel will shorten the drive from Xiamen to Xiang'an from 1.5 hours to eight minutes.

Designed and constructed domestically, the project encountered many challenges not found in other international tunnel projects. Guo Yanjing, leader of this project explained that, at certain points of the tunnel, the most shallowest areas are 5.7 meters below sea level; and the amount of surrounding rocks, waterfalls and layers of mineral deposits is large and the most rare in the world.

The most advanced technology was used in the construction of the tunnel, which also ensured safety of the construction workers. This tunnel has strong resistance to corrosion and water leakage, and can also withstand an 8.0-magnitude earthquake, reaching an international level.

The completion of this tunnel is a milestone for China in exploring undersea tunnel construction technology for similar projects.