Once a year, thousands come to China’s Hangzhou Bay to witness a freakish sight – an annual tidal wave. Under the late summer’s full moon, the tide in the bay surges. Even in a normal year, it’s an awesome display. But this is not a normal year. When the wall of water arrives, it’s more than 9 feet high, and it closes in fast. With a force like a locomotive, the wave sweeps dozens away instantly. Others try to out run it, only to be overtaken. In all, it engulfs 30 people. Amazingly, while a few barely escape drowning, no one is killed.