So, what exactly is going on here? According to CNN, researchers aren't entirely sure what's behind the green invasion. One expert told the network that it's possible that the lush green algae plume may have something to do with "the change in the environment," but is mum when it comes to specifics.
Regardless, the bright green goop has inspired a slew of amazing photographs. In some photos, the algae, which now covers 200 square miles of the Yellow Sea, looks so thick that it resembles a fairway on a golf course. You can check out a collection of photos below.