Biscuit Basin

Biscuit Basin is a geothermal area in Yellowstone National Park, north of Old Faithful, known for vivid hot springs and small geysers. Sapphire Pool’s deep-blue water is a standout, with Mustard Spring, Jewel Geyser and other thermal features nearby. Boardwalks once led visitors across fragile ground, but the basin is closed following a hydrothermal explosion in 2024 that damaged the boardwalk and parking area. Check current access information before planning a stop; nearby Black Sand Basin is an alternative.

Thermal features at Biscuit Basin

Biscuit Basin lies in the Upper Geyser Basin area, north of Old Faithful. Its name comes from the biscuit-like mineral deposits that once surrounded Sapphire Pool. Those formations were scattered when the pool erupted in 1959, after the Hebgen Lake earthquake.

Sapphire Pool remains the area’s signature feature: a large, deep-blue hot spring. Other named thermal features include Mustard Spring, Jewel Geyser, Avoca Spring, Shell Spring, Black Opal Pool and Black Pearl Geyser. The area’s springs and geysers sit among fragile geothermal ground, which is why boardwalks were used to guide visitors.

Closure and nearby alternatives

A hydrothermal explosion at Black Diamond Pool on July 23, 2024, damaged the boardwalk and nearby infrastructure. Biscuit Basin has remained closed, with access restricted for safety. Check the park’s current information before setting out, as the available material does not establish a reopening date.

Black Sand Basin is nearby and can make a useful alternative stop while Biscuit Basin is inaccessible. When Biscuit Basin is open, its trailhead also provides access to the Mystic Falls hike and the Biscuit Basin Overlook. Confirm trail access before including those routes in your plans.