The Xihoumen Bridge is a suspension bridge built on the Zhoushan Archipelago, the largest offshore island group in China. The main span was completed in December 2007. The entire bridge, along with Jintang Bridge, was opened to traffic on a test basis on 25 December 2009. It is the second-longest suspension bridge ranked by the length of the centre span. The opening date was delayed due to a ship collision on 16 November 2009 that slightly damaged the side of Jintang Bridge.
The 5.3-kilometre-long suspension bridge connection has a 2.6-kilometre-long main bridge with a central span of 1,650 metres. The approaches total 2.7 kilometres. When it opened, there was only one bridge with a larger span, the Akashi-Kaikyo Bridge in Japan.
The bridge was built by the province of Zhejiang, at a cost of 2.48 billion yuan (approximately US$363 million). Construction began in 2005, and the first traffic crossed the bridge on 25 December 2009, at 11:58 p.m., local time.
The Xihoumen Bridge links Jintang and Cezi islands. Another bridge, the 27-kilometer-long cable-stayed Jintang Bridge, links Jintang Island and Zhenhai of Ningbo. The two bridges are the second phase of a huge project started in 1999 to link the Zhoushan Archipelago to the mainland with five bridges. Construction of the other three bridges has been completed.