Exploring the Hidden Gem of Raja Ampat: Kali Biru - The Blue Crystal Clear River

The fame of Kali Biru stems from its naturally blue-hued waters, a phenomenon that has intrigued both locals and visitors alike. Referred to as “Warabiae ” in the local language, meaning a clear blue river, Kali Biru owes its distinctive colour to the sunlight’s interaction with its waters. When sunlight penetrates the river’s surface, water molecules absorb the longer red waves, followed by yellow, green, and purple, with the blue waves being absorbed last. The water in Kali Biru however is high in the mineral Calcium Carbonate which affects the colour absorption balance to favour the colour blue, thanks to the limestone karst geology at the rivers source. This absorption process results in the mesmerising blue hue that greets the eyes of those who visit. In addition there is very little algae and sediment which also contributes to the brilliant blue colour, as the river is reasonably fast flowing, originates from a large spring and is surrounded on all sides right up to the banks by dense rainforest.