Limmat river

The Limmat river commences at the outfall of Lake Zurich, in the southern part of the city of Zurich. From there flows in a northwesterly direction, continuing a further 35 km until it reaches the river Aare.

Lots of swans swim in it and the water is very clear as you can see.
Technically on one of the photos you can see the swan's head when s/he dived for some grubもっと詳しく