Visit Grand Prismatic Spring | Wyoming, USA
Look down on a pool of impossible colour: a deep blue centre fading through green and yellow to burnt-orange microbial mats, with steam moving across the surface and Yellowstone forest beyond. Grand Prismatic Spring is the largest hot spring in the United States and one of the clearest demonstrations that geology and living organisms can create the same spectacle. See it from two perspectives. Midway Geyser Basin’s boardwalk brings you close to the textures, runoff channels and scale of the spring, while the signed overlook reached from the Fairy Falls trail reveals its full oval shape when the air is clear. Steam, wind and season affect visibility, so no photograph is guaranteed. Stay on the boardwalk and designated paths without exception. The water can cause fatal burns and the thin ground around thermal features may conceal boiling water. Carry water, sun and weather protection, allow for traffic and full car parks, and never approach wildlife for a better picture. For a UK traveller this is normally part of a wider Yellowstone journey rather than a standalone stop. Check current National Park Service road, trail, fee and safety information before setting out, then give the basin enough time to understand what you are seeing rather than simply collecting the famous view.