Matsu Islands
Credit: WanRu Chen

What have been described as “blue tears” have become a major tourist draw on the Matsu Islands.

The phenomenon creates glowing blue waves along the shores of the islands, which are off the coast of Taiwan.

While recent speculation focused on pollution as the cause, Professor Chiang Kuo-ping, director of the Institute of Marine Environment and Ecology at the National Taiwan Ocean University announced the results of a study that found the cause to be the presence of noctiluca scintillans—a type of glowing algae—in the water.

“This represents a kind of ecological balance, and the appearance of noctiluca scintillans is therefore far from an indication of environmental deterioration,” he said.

The study began earlier this year as researchers sought an explanation for the glowing water, according to the Taipei Times.

Erika Owen is the Senior Audience Engagement Editor at Travel + Leisure. Follow her on Twitter and Instagram at @erikaraeowen.