A giant green monster is invading beaches in China, turning what should be paradise into something out of a nightmare.

The green, slimy substance of the beaches of Qingdao, China, the South China Morning Post reported, creating an alien playground for seemingly excited beachgoers. But while it may seem all fun and games, the algal bloom, otherwise known as Enteromorpha prolifera, is actually quite harmful to the environment and potentially humans, as well.

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Large algae quantities rob the water of oxygen, around, says CityLab. The fiscal cost is staggering, with millions of dollars spent on damages and cleanup caused by the bloom.

Humans are not at immediate risk from the algae, according to the International Business Times. However, when it decomposes, Enteromorpha , which could prove dangerous.

Scientists believe an along Qingdao’s coast may be to blame for the massive bloom, says the Morning Post. Coastal pollution has also been said to be a possible cause.

The bloom has overrun the area annually since 2007, but beachgoers seem determined to enjoy their beach holiday along one of China’s most celebrated coastal towns.

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