By far the most spectacularly colored water in Yellowstone is this hot spring. There must be a particularly large algae colony of Rhodophyta (Red algae) in this water, because the color was so vivid. Since the presence of algae depends upon the degree of heat in the water, coloration is a byproduct of this heat as well. As you can see from the steam rising in the background, this spring is very hot. I used the 35mm end of my zoom on this shot. This focal length is probably the most commonly used focal length of them all, because so many zoom lenses begin at 35mm. It is wide, but certainly not a true wideangle. I would call it a semi-wideangle or semi-normal lens. It certainly does its job in this image. It allows me to get close enough to the algae to make detail work, yet I am also able to get a significant amount of it into the frame. It also lets me include important background context. Grand Prismatic Spring is still recovering from the 1988 wildfires that scorched this area. Note all the fallen trees on the hills beyond. We have the ugly and the beautiful, side-by-side. The 35mm wideangle lens makes it all happen here.