It's raining and the wind is blowing, but out in the middle of the water four international big wave surfers await the oncoming surge. The wave arrives and the surfers mount their boards, riding it as long and as far as they can. However, this is no ordinary wave. They're riding the silver dragon, the Qiantang tidal bore.

Every year around the time of the mid-autumn full moon, hundreds if not thousands of people line up on either side of the Qiantang River in Zhejiang province to watch the annual tidal wave known as the tidal bore. A tidal bore is when an ocean wave travels up a narrow path against the regular current of the water. This usually happens in rivers.

Commonly known as the Silver Dragon, the Qiantang River tidal bore happens to be China's and the world's longest inland surge.