For people living in the Yangtze River delta area, there is a time-honoured tradition to follow on the Mid-autumn festival---tide watching.

The world’s largest tidal-bores surge across the Qian-tang River in Hai-ning county, east China’s Zhejiang Province at this time of year. The bores usually start at the beginning of the eighth lunar month and reach their peak on the eighteenth day, which falls on October the 3rd this year.

The tides produce a thunderous, roaring sound, thrilling tens of thousands of spectators each year. The tides are a world-renowned natural wonder caused by the gravitational pull of the moon, and the funnel shape of Hangzhou Bay.

The centrifugal force produced by the rotation of the earth, and by the peculiar bottleneck shape of Hang-zhou Bay makes it easy for the tide to come in, but difficult for it to ebb. Qian-tang River, along with the Amazon in Brazil and the Ganges in India, have the largest bores in the world.

For people living in the Yangtze River delta area, there is a time-honoured tradition to follow on the Mid-autumn festival---tide watching.

For people living in the Yangtze River delta area, there is a time-honoured tradition to follow on the Mid-autumn festival---tide watching.