Solitary Geyser is named for its somewhat secluded location, several hundred yards away from most of the other geysers in the Upper Geyser Basin. It is large in size but only erupts to a height of a few feet. There are many interesting deposits around its perimeter, as you can see in the photograph.
This geyser is also considered an objective lesson in how human tampering can permanently change geothermal features. When Yellowstone National Park first opened, Solitary was a dormant hot spring. Water was diverted from the spring to fill a swimming pool, which lowered its water level sufficiently to cause it to start erupting. Even when this change was later undone and the original water level restored, the internal plumbing of the spring had changed so much that it has remained a geyser ever since, erupting every 5 minutes or so.