Swiss waters are mostly blue, green, or turquoise, depending on the time of day and season. Its beautiful color results from glacial particles known as "rock flour" which reflect the blue-green sector of the light spectrum.
Glacier particles are tiny, sinking slowly to the bottom. The purity of the Aare River water also allows these particles to easily enter and diffuse. The colors of the rivers and lakes are said to be most beautiful in spring, when they are turquoise or emerald when the glaciers begin to melt.
Quoted from Got This Now, with the onset of warm weather, most of the water in Switzerland's rivers, including the Aare River, comes from melting snow and ice in the mountains. This water is enriched with minerals from the rocks where it flows and turns a beautiful light turquoise color.
The river empties into the Aare Glacier in the Bernese Alps in the Canton of Bern, under the Finsteraarhorn and west of the Grimsel Pass, in south-central Switzerland. As Aare flows north past Meiringen, the river divides the beautiful Aare Gorge. After turning west, it extends into the glacial Lake Brienz.
As previously mentioned, Switzerland's rivers and lakes have excellent water quality, including the Aare River. This has been confirmed by water samples which resulted in placing the Aare River in the "very good quality" category according to the European Union in 2016. This is a special attraction for the Aare River so that people do not have to worry about accidentally swallowing water while swimming there.