Grand Prismatic Spring - Located in the Midway Geyser Basin, Grand Prismatic can only be photographed in its entirety from way up on the side of the adjoining hillside or via aerial view. It's huge! This is only a small, but colorful, portion. We spent an enjoyable day touring friends Ellen and Donald around the park, seeing plenty of wildlife, Old Faithful Geyser (of course) and plenty of other scenic delights. We finished off the day with baked trout encrusted with crushed pistachio nuts and parmesan cheese at the Mammoth Hot Springs Hotel. Yum!