August 18 on the Chinese lunar calendar is always a big day in Haining， Zhejiang Province. On this particular day of year， the highest tides surge from the East China Sea through the hundreds-of-thousands-of-meters-wide Hangzhou Bay and come to Haining， where the Qiantang River suddenly becomes narrow. The surging tides are really a breathtaking spectacle. Before a railroad was built between Hangzhou and Shanghai in 1909， watching the tides on this particular day was mainly a local event， although its fame had long since been known nationwide through various poems including some by the Emperor Qianlong of the Qing Dynasty (1644-1911).

For this reason， a big part of the poems on the river phenomenon before the Republic of China (1911-1949) were written by local poets. In ancient times， however， for a long while， tide waves came up the river all the way to Hangzhou. Watching tides， therefore， was a big event in ancient Hangzhou in mid August. Mountains along the Hangzhou-section of the river were the vantage spots where local residents came to view the autumn tides. This is why the best ancient poems about the river tides were written by the poets who witnessed the tides in Hangzhou. These great poets include Bai Juyi， Su Dongpo， Mi Fu， Feng Menglong， and Zheng Xie.

How far river tides reach upstream all the way into the Qiantang River depends on various factors even though river tides in Qiantang River have taken place twice a day since time immemorial. The biggest tides take place in the first four days of a month on the lunar calendar and then from the 16th day to 19th day again.

Tides have constituted a problem since ancient times up to present day. They have caused disasters. Building dikes have been a big issue for thousands of years in Haining. Huge tides on August 18， 1953 threw a 1.5-ton iron bull statue off a dike and shoved it in the river for more than 10 meters. In 1978， two cameramen from Beijing Film Studio came to shoot a documentary on the tides in Haining in lunar August and were swept into the river. They were saved but the camera was not. In lunar August 1991， powerful night tides destroyed part of the river dike near Yanguan.

After the railway connected Haining with neighboring cities， more people came to Yanguan， the previous capital of Haining. On lunar August 18， 1916 (September 15)， Dr. Sun Yat-sen， his wife and many of his friends came to Yanguan to watch tides. On lunar August 18， 1923 (September 29)， the poet Xu Zhimo， a local of Haining， invited his friends to watch tides at Yanguan. His diary kept a detailed account of the tour. After the founding of New China， Mao Zedong and many other top state and party leaders came to see the tides at Yanguan. Mao Zedong took special trips to Hangzhou to watch tides in the sprig of 1954 and on lunar August 18 (September 11)， 1957.

Today， on big days in August， extra trains carry spectators all the way from Shanghai and Hangzhou to Yanguan to watch the river tides.#8194;□