Castle Geyser in the Upper Geyser Basin of Yellowstone is the worlds largest geyserite sinter cone.
This sinter cone is thousands of years old, sitting on an even older platform and is the largest sinter formation in the world. Castle erupts every 13 hours for 20 minutes and its fountain reaches a height of 75 feet (24 m).
The light of dusk is additionally caused by smoke of a nearby forest fire. The smoky scenery reflects in the calm waters of the geyser.