In Costa Rica, Turquoise River Creates Amazing Natural Optical Illusion

Located in a national park in Costa Rica, Central America, it is no wonder that the Celeste River takes its name: the vivid blue of its waters makes it one of the most beautiful watercourses on the entire continent. And when looking at images of the place, it's not hard to imagine why it arouses such fascination.

Crystal clear to some extent, the river takes on a bluish tint at a specific point called Teñideros, at the confluence of two other rivers: the Buena Vista and the Roble. After that, it winds for 14 kilometers through the dense and untouched tropical forests of the country.

For a long time it was believed that their unusual color was caused by chemical compounds such as copper and even sulfur. But after years of unfounded speculation, a team of scientists from the National University and University of Costa Rica in 2013 finally managed to unravel the mystery behind the intense blue of its waters.

According to Costa Rican experts, it was all a great optical illusion caused by the chemical reactions of mixing sulfuric gases with calcium carbonate - substances released by the nearby Tenório volcano. In addition to deceiving the human eyes, these reactions give off an intense odor that can be noticed by tourists who come there.