Every year during the Mid-Autumn festival, the world's largest tidal bore hits the Qiantang River in east China's Zhejiang Province. The spectacular scene draws tens of thousands of people from both home and abroad. This year, as usual, it gave a thrilling experience as to the power of Mother Nature.

The low but powerful sound from the horizon suggests the arrival of the world's largest tidal bore on the Qiantang River.

The upcoming tide forms a wave that travels up a river or bay, against the current. The one in Qiantang was 9 meters high, and travelled at 40 kilometers per hour.

To have a better view of the spectacular scene, 150-thousand people from both home and abroad line the river's banks.

A visitor said, "I came from Jiangxi province. This is my first time to see the tidal bore. I came here early in the morning."

Another visitor said, "I come to see the tide every year. I felt this year's bore is larger. "

The tidal bore is caused by the attractive force between the moon and the sun. Around each year's Mid-Autumn Festival in China's lunar calendar, the sun and the moon stand along the same line. This particular position causes a peak in the tidal bore.

Geographical features also contribute to the forming of the phenomenon. The unique bottleneck shape of Hangzhou Bay, allows turbulent sea water into a narrowing water channel, creating the stunning, but often hazardous tides.

At different locations, the bore presents different forms, such as a Thread-shaped tide bore, Crossed tidal bore, and the returned tidal bore.

The viewing tradition in China dates back more than 22-hundred years, and became popular during the Tang Dynasty.

Now, the swirling waves still amazes many who came to east China to get a feel of what nature can offer.