While hiking in the Swiss Alps, I noticed a small river, rather hidden from view, that had a bright red color. I immediately went to look, and indeed the river was red. However, the color was not given by the water, which was perfectly transparent, but by the bottom of the river, covered with red algae, which made the scene impressive and somehow disturbing. I took a few pictures with the camera, but I immediately thought about how it would make that scene from above. So, I pulled the drone out of my backpack and took a few photos with it as well.