Highly acidic thermal spring known for its vibrant colors, intense sulfur activity, and one of the lowest pH levels measured in Yellowstone's geothermal system.
Private vehicle: $35 (7-day pass)
Motorcycle: $30 (7-day pass)
Individual (walk/bike): $20 (7-day pass)
Annual Yellowstone Pass: $70
How to Get There
From Cody (60 mi): Follow US-14/16/20 west through Yellowstone's East Entrance, continue toward the Mud Volcano area on the Grand Loop Road, and stop at the Sulphur Caldron overlook located beside the roadway.
Overview
The Sulphur Caldron is one of the most chemically extreme geothermal features in Yellowstone National Park. Located within the Mud Volcano thermal area, the spring contains highly acidic water created when underground hydrogen sulfide gas mixes with groundwater and converts to sulfuric acid. The result is a churning, steaming pool with a distinctive yellow-green appearance and a powerful sulfur odor that immediately captures visitors' attention. The feature is among the most acidic thermal waters found in Yellowstone, demonstrating the remarkable diversity of conditions produced by the park's underlying volcanic system.
Visitors can observe Sulphur Caldron from nearby boardwalks and roadside viewpoints while exploring other attractions within the Mud Volcano area. Rising steam, bubbling water, and bright mineral deposits create a dramatic landscape that highlights the ongoing interaction between heat, water, gases, and rock deep beneath the Yellowstone Plateau. Combined with nearby features such as Dragon's Mouth Spring and Mud Volcano, Sulphur Caldron offers a compelling glimpse into the powerful geological forces that continue to shape one of the world's most active geothermal regions.
This article uses material from the Wikipedia articles and official tourism pages for the Mud Volcano Area and Yellowstone National Park, which are released under the .org/licenses/by-sa/3.0/">Creative Commons Attribution-Share-Alike License 3.0.
