China is in the seventh year of a gargantuan algal bloom off the coast of the eastern city of Qingdao, and this year's growth set a record: green sludge covers 11,158 square miles, more than twice the previous record of 5,109 square miles. Such algal blooms are caused by an excess of nutrients in the water, which can be due to the addition of human waste, industrial pollution, and agricultural byproducts.

Algal blooms can block sunlight and suck all the oxygen out of an ecosystem, which is detrimental to marine life. However, scientists say this particular algae, enteromorpha, isn't harmful to humans. That's perhaps why so many Chinese seem eager to frolick in the goop even as government cleanup vehicles attempt to scoop it up.