The strikingly blue color looks almost out of this world but it’s real. The Rio Celeste gets its baby blue hue from a natural chemical reaction that occurs between minerals in this volcano-rich region. Access to the Rio Celeste River and Waterfall is via the jungle trails at Tenorio Volcano National Park. It is a moderately difficult hike along an often muddy, shaded path to reach the staircase that leads to the waterfall. A short climb down 250 stairs gets you to a viewing platform.
Source: twoweeksincostarica.com