Black Sand Basin Trail

Black Sand Basin is an easy, roughly half-mile walk through a branching network of boardwalks and short spurs. Allow about 30 minutes to visit the pools and geysers, then return to the parking area along the shared paths. It is not one clean loop; the total depends on how many side branches you explore. The separate one-mile walk from Daisy Geyser is an approach to the basin, not this short visit.

The boardwalk threads past Rainbow Pool, Emerald Pool, Sunset Lake and Cliff Geyser beside Iron Spring Creek. Cliff Geyser can erupt frequently, sometimes sending water about 40 feet up, but its timing is irregular. Sunset Lake is also a geyser; eruptions are uncommon and often hidden by steam. The pools' bright edges come from heat-loving microbes, while the basin's black sand is volcanic glass called obsidian. From the boardwalk, Sunset Lake's orange rim makes a striking frame around its blue water.

Use the Black Sand Basin parking area along the Grand Loop Road, about a mile northwest of Old Faithful; the boardwalk starts beside the lot. The short walk sits around 7,300 feet and is mostly level, though the National Park Service notes a few steep boardwalk sections. The area is listed as wheelchair accessible, but those grades may need assistance.

Thermal water can cause severe burns. Stay on boardwalks and designated paths, keep children supervised, and do not run or push. Pets are not allowed on the boardwalk or in thermal areas.