It's a natural phenomenon along a coast where a river empties into an ocean or sea and is essentially a strong tide that pushes up the river, against the current.
The tides usually reach their peak between the 15th and 18th day of the eighth lunar month with spectacular scenes to delight the crowds. Waves of up to nine metres can be generated, but this year they were only 0.3 metres high.
It's part of the Mid-Autumn Festival, an occasion when families get together, eat traditional mooncakes, light up lanterns and celebrate good harvests, according to state broadcaster CCTV.
