The Qiantang River (tch'yen-tang), formerly known as the Hangchow River or Tsientang River, is a river in East China. An important commercial artery, it runs for 459 kilometers (285 mi) through Zhejiang, passing through the provincial capital Hangzhou before flowing into the East China Sea via Hangzhou Bay south of Shanghai. Its original name, the "Zhe River" or "Zhe Jiang", is the origin of the name of Zhejiang province. The river is also known, along with Hangzhou Bay, for having what is called by locals as the "Silver Dragon", the world's largest tidal bore, a phenomenon where the leading edge of the incoming tide forms a wave (or waves) that can rise to a height of 9 meters (30 ft) and travels up the river or narrow bay at top speeds of 40 km/h (25 mph; 11 m/s) against the direction of the river or bay's current, and can be seen from miles away.