Which river has the highest tidal bore in the world?

The Qiantang River has the world's highest and largest tidal bore. This dramatic wave forms when the incoming tide surges from Hangzhou Bay into the river's narrowing, shallow channel in Zhejiang, China.

The bay's funnel shape concentrates tidal energy, while the riverbed's sandbars and changing channels help steepen the advancing wave. The bore can reach about 9 metres high and travel upstream at speeds approaching 40 kilometres per hour. It is often called the Silver Dragon.

The spectacle has been observed for centuries. Traditional viewing peaks around the 15th day of the eighth month of the Chinese lunar calendar, when the autumn tide is especially strong. The Qiantang bore is sometimes confused with the Severn Bore in Britain, another famous tidal wave, but the Severn is smaller. The Qiantang is also associated with one of the world's oldest known tide tables and remains a major tourist attraction.