Crowds gathered along the Qiantang river in Hangzhou, China, on 27 July to watch the “Silver Dragon” pass. This is no fire-breathing monster, though, but a tidal bore, a phenomenon where a tidal wave from the sea enters a river and reverses its current. This is the world’s largest bore, with waves that can reach 4 metres tall – and larger if it hits an obstacle – and travel at up to 10 metres per second.
