You cross over the Firehole River to get to the Midway Geyser Basin. Like all of the rivers, it was raging. Wandering through Yellowstone's thermal areas, you'll see an amazing range of colors. The centers of the hot springs may be deep blue or blue-green or palest turquoise blue. The edges of the pools and their runoff channels will range from yellow through orange and red to brown, with lite and dark green here and there.
Videos show these much better than photos, so there are mainly videos here. They still don't really do justice to the beauty though.