Costa Rica: Rio Celeste in a Volcan Tenorio National Park

An absolute must-do hike in Costa Rica is the hike to Rio Celeste in the Volcan Tenorio National Park. This is an absolute gem – the hike though the virgin primary rainforest of massive trees, everything dripping with water, fog and clouds covering everything, and rain never stopping. The hike leads to a waterfall, hot springs, a boiling pool, and other water features along Rio Celeste, which is famous for turquoise coloration of the water. The color phenomenon is actually quite unique and known as Mie Scattering – here two rivers combine: one is carrying high concentration of minuscule and invisible aluminosilicate particles, while the other stream has very high acidity due to volcanism. The mixing causes a rapid drop in pH, which literally bakes the particles into bigger pieces that become visible and taint the water almost fluorescent turquoise.