PHOTOS: Qingdao natives frolic in annual tide of green algae

China's coastal northeastern cities of Qingdao and Rizhao have been hit every year since 2007 by green waves of sea algae invading their shores; and this year is no exception. While the source of this mysterious algae bloom is still unknown, the New York Times has previously issued the hypothesis that our beloved sushi could be to blame.

The theory is that nearby farms of porphyra, the seaweed in sushi, attract the green algae that later forms those impressive carpets of sea grass.

But rather than running from the slimy green mess, enthusiastic locals treat the annual arrival of the green sludge as another beach attraction, diving in, covering their whole body with the stuff, with some hungry ones even taking a bite...

However, the algae releases toxic hydrogen sulfide gas once it begins to decompose, which can be harmful to humans (not to mention quite pungent).

Qingdao reportedly removed some 19,800 tons of algae in 2013 and spent $30 million on the cleanup operation in 2008.

Luckily, this isn't a year-round pastime...

[Images via Quartz and Digital Journal]