The Mawan Undersea Tunnel, the first underwater tunnel in Shenzhen, Guangdong province, was officially opened on Tuesday. The tunnel, spanning approximately 8.05 kilometers, connects Qianhai cooperation zone in the south with the Dachan Bay Port Area in the north.

The project has garnered more than 85 awards and achieved several breakthroughs in highly challenging tunnel technology, local authorities said.

It consists of two sea-crossing shield tunnels with a maximum excavation diameter of 15.5 meters, making it the largest diameter shield tunnel under the sea in China.

The completion of the project connects the freight transport channel of Nanshan Port Area in Shenzhen while also integrating passenger transport in the Mawan, Chiwan and Dachan Bay areas.

The tunnel, with six lanes in both directions, will help reduce traffic jams in Qianhai. Freight traffic to and from Nanshan Port will be redirected through the tunnel, separating it from the passenger traffic in Qianhai and Bao'an CBD. This will enhance the urban environment in these areas, said Shen Haiyang, an engineer from the city's transportation public facilities construction center.

It is also a key demonstration project for the connectivity and transportation construction in the Guangdong-Hong Kong-Macao Greater Bay Area, local authorities said.