During my recent trip to China, a friend took me to a scenic little town called YanGuan. The town owes its fame to being the best spot to watch Qiantang’s Tidal Bore（钱塘江潮） . The cause of the tidal bore is water from Hangzhou Bay (杭州湾) that travels up the Qiantang River（钱塘江）. The narrowing of the river, from 100km at its mouth to only a few kilometres inland, and a gently rising riverbed, means that the water is constricted and a large wave is created. The tidal bore, also known as the Black or Silver “Dragon”, holds the world record reaching a height of 8.9m and a speed of 40km an hour.
Of course, actually seeing the bore depends largely on luck: a combination of moon and high tide in reality, which occurs at certain times of the month throughout the year. The Mid Autumn Festival, home to the fullest moon, is traditionally associated with viewing this phenomenon.
Although I was not visiting at the right season, the scenic little town and a small line of tide bore approaching from a distance with loud sound are still memorable.
I have heard of the Qiantang Tidal Bore, which is the biggest in the World. The largest in Europe is that on the River Severn in South West England, which is highest near the equinoxes – a website details times and height predictions. I attach some pictures from a few years ago taken near a pub, conveniently located near a good viewing site. The bore is particularly popular with surfers, and I believe the world record for longest wave ride was recorded there.