Hangzhou Bay is where Qiantang River flows into the sea. It is trumpet-shaped, with a width of 100 km, and gradually shrinks to about 20 km to the west. The narrowest place is near Yan Guan Town, Haining County, only 3 kilometers wide. When the tide came in, it had to be piled up due to the constraints of the topography on both sides of the strait, and the tide head was piled up higher and higher, like a vertical water wall, pushing westward.

At the same time, due to the action of tidal current, a large amount of sediment spilled into the sea from the Yangtze River is brought to Hangzhou Bay continuously, forming a huge "sandbar" like a threshold at the mouth of Qiantang River. When the tide rushes to the mouth of Qiantang River, it is blocked by sandbars, forming a world wonder that the waves behind push the waves in front, one after another, surging and overwhelming!

"August 18th tide? A spectacular westward journey. " This is an eternal famous sentence of Su Dongpo, a great poet in the Northern Song Dynasty, praising the autumn tide in Qiantang. For thousands of years, Qiantang River has attracted many tourists with its unique and extraordinary trend.