Dongtan, Planned eco-city site in Chongming District, China

Dongtan was a planned eco-city on 86 km² at the eastern tip of Chongming Island, near the mouth of the Yangtze and the Chongming Dongtan National Nature Reserve. It was never built: by 2010 only some developer offices, wind turbines and greenhouses marked the site. A cable-stayed bridge and tunnel to Chongming opened in 2009.

Dongtan was designed from 2005 by the British firm Arup for the Shanghai Industrial Investment Corporation, with the contract signed at 10 Downing Street in November 2005 before Tony Blair and Hu Jintao. The first phase, a marina village for 20,000 people, was to be shown at the 2010 World Expo, but work stalled and the city was never built. The 2008 corruption conviction of backer Chen Liangyu removed political support.

The name Dongtan (东滩, "east shoal") marks the site at the eastern tip of Chongming Island, beside the Chongming Dongtan National Nature Reserve, a staging ground for migratory birds flying from Siberia to Australia, including the rare black-faced spoonbill. Only promoters' offices, wind turbines and greenhouses stood on the spot before the plan was frozen.

The location is not easily accessible today since infrastructure is still being developed and most areas remain closed to visitors. A planned metro connection will eventually link it to Shanghai's transportation network.

The original vision included a completely carbon-neutral city powered by wind turbines and waste-to-energy systems. This approach represented an innovative take on sustainable urban planning at the time.