Costa Rica’s Rio Celeste (Sky River) is very aptly named for it’s beautiful sky blue coloration.
This is the spot where the Rio Celeste takes on its unique hue.
A chemical reaction between two merging streams, happening in just the right way, causes the color change to blue in the downstream river.
The exact circumstances causing this reaction are apparently unique to this spot, because taking water samples from the two streams and mixing them does not result in blue water.
To get here involves a decent hike, but is very much worth it.