The naturally occurring phenomenon happens in Arous (Bride) Lake, located in Halimeh Jan village of Roudbar country.
The lake changes colours because of a type of green microalgae.
Before noon, the lake is green, like the jungle surrounding it, because the microalgae cover the surface of the water.
In the afternoon, as the wind starts blowing, microalgae go down and the lake becomes blue.
What follows are photos of the magnificent lake: