Lake Tai (literally "Grand Lake") is a large lake in the Yangtze Delta plain, on the border of the Jiangsu and Zhejiang provinces in the People's Republic of China. The waters of the lake belong to the former in its entirety with part of its southern shore forming the boundary between the two provinces. With an area of 2,250 km² and an average depth of 2 metres, it is the third largest freshwater lake in China, after the Poyang and Dongting Lakes. The lake houses about 90 islands, ranging in size from a few square meters to several square miles.
Lake Tai is linked to the renowned Grand Canal. The lake is also the origin for a number of rivers, including Suzhou Creek. In recent years, Lake Tai has been plagued by pollution as a result of rapid economic growth in the surrounding region.
According to many guidebooks, Lake Tai is best seen from the scenic viewpoint in Xihui Park (錫惠公園)in the west of Wuxi (無錫), from the top of Dragon Light Pagoda (龍光塔 Lóng Guāng Tǎ), from which both Wuxi and Lake Tai are visible. Another wellknown panoramic view is from Longshan (Mt Long), where famous ancient poet Su Shi once wrote a poem.
Three of the lake's islands are known as the Sanshan Islands ('three hill islands'), one of the Chinese National Geological Parks.
Yuantouzhu is another prominent region for tourists. It received this title because its outline resembles a turtle head. The region gained its fame in the early 20th century and it contains more than ten scenic sites for visit.
In May 2007, the lake was overtaken by a major algae bloom and by major pollution with cyanobacteria. The Chinese government has called the lake a major natural disaster despite the clearly anthropogenic origin of this environmental catastrophe. With the average price of bottled water rising to six times the normal rate, the government has banned all regional water providers from implementing price hikes. The lake provides water to 30 million residents, including about one million in Wuxi. As of October 2007, the Chinese government had shut down or given notice to over 1,300 factories around the lake. Notwithstanding this official increase of governmental concern, one of the leading environmentalists who has been publicizing the pollution issues of the lake, Wu Lihong, has now received a three year prison sentence after being arrested and tried for alleged extortion of one of the polluters. Jiangsu province now plans to clean up the lake. At a cabinet level chaired by Wen Jiabao, the State Council set a target to clean Lake Tai by 2012.