Black Sand Basin is an isolated group of geysers and pools in Yellowstone National Park’s Upper Geyser Basin. This section of the UNESCO World Heritage listed park has an accessible ¼ mile trail. This entry focuses on just a few of the geysers and pools in the Black Sand Basin.
From the parking lot, the first feature encountered is a small spring, Jagged Spring. It’s in near-constant activity but almost never erupts. The spring appeared in the 1930s and the smaller Ragged Spring is behind it.
A short walkway takes you to the edge of Iron Spring Creek where you can get a good look at Cliff Geyser. This unpredictable geyser can erupt for 30 minutes to three hours with a height of 40 feet. It’s named after its setting which looks like it’s at the edge of a cliff.
Continuing along the main path to the left is Green Spring. It’s usually a very calm greenish colored pool, although it is known to erupt. Eruptions are extremely rare, with the first recorded one in 1934. The spring doesn’t look very interesting and I was more intrigued by the colors on the cliff in the background.
At the left fork in the path is the most beautiful feature at Black Sand Basin. Emerald Pool is a rich green pool with a depth of 25 feet. Unfortunately, vandalism has caused the temperature to drop to about 154°F. Further temperature drops could cause the pool to lose the emerald green color it’s named for.
Back along the path on the right fork, Rainbow Pool is a huge 100ft x 130ft pool with a depth of 27 feet. The edges of the pool resemble the colors of the rainbow. In front of it is Handkerchief Pool. It was a very popular pool in the early days of the park but has been permanently damaged since 1929. Visitors were encouraged to drop handkerchiefs at one end of the pool where convection currents would suck it down into the vent. The handkerchief would spin around a bit and pop back up to the surface nicely laundered.
The final feature, Sunset Lake, is the largest pool in Black Sand Basin. It measures 145ft x 191ft. It usually has a steam cloud hovering above it, sometimes making it difficult to see all of the colors. I was lucky during my visit.