Biscuit Basin - Where the Ground Exploded

A stop on Yellowstone Geyser Country, a free self-guided tour.

Biscuit Basin shows how fast geyser country can change. On the morning of July 23, 2024, water beneath Black Diamond Pool suddenly flashed to steam. A dark column of steam, mud and rock shot hundreds of feet into the air, destroying part of the boardwalk while visitors watched. Remarkably, no one was hurt. Scientists stressed that it was not a volcanic eruption but a hydrothermal explosion: the same pressure-cooker physics as a geyser, released all at once.

The basin has been closed since the blast, and in June 2026 a smaller explosion just north of Black Diamond Pool cracked the ground again. Check nps.gov to see whether the parking lot and boardwalk have reopened before you plan to stop.

The name tells another story of change. Knobby, biscuit-shaped mineral deposits once ringed Sapphire Pool, but after the 1959 Hebgen Lake earthquake the pool erupted violently and washed most of them away. If the basin is closed, don't stop on the road; take in the steam as you drive past.

Getting here: Continue north on the Grand Loop Road about 2 miles; the Biscuit Basin parking area is on the left, if it is open.

Did you know?: The 2024 explosion threw rocks tens to hundreds of feet, and the largest blocks tumbled toward the Firehole River.

Photo op: Only from open, designated areas: if the boardwalk has reopened, frame Sapphire Pool's blue against the steaming basin; if not, skip the photo rather than pull over on the road.

Nearby: No services while the basin is closed; the nearest full services are back at Old Faithful.

More on Wikipedia: Geothermal areas of Yellowstone · 1959 Hebgen Lake earthquake

Biscuit Basin - Where the Ground Exploded

Stops on this tour