Mud Volcano Area, Yellowstone National Park

Mud Volcano at Yellowstone National Park spews steam from a blue-gray mud pool surrounded by a rocky crater.

Mud boils and steam hiss along the boardwalk. Sulfur Caldron and Dragon's Mouth Spring vent steam and mud, while the air carries a rotten-egg scent. This hydrothermal patch sits in the Yellowstone Caldera near a resurgent dome—ground deformation is ongoing. Magma heats groundwater, creating acidic chemistry that dissolves rock into the clay-rich mud that churns beneath pressure.

Access & viewing

GPS Coordinates: Varies
Accessibility: Lower loop wheelchair accessible; northern sections paved but steep; stairs at northern end

Conditions & safety

Permits Required: 0

Planning advice

Nearby Attractions: Dragon's Mouth Spring; Sulfur Caldron; Hayden Valley; Fishing Bridge
Nearby Facilities: Parking lot; vault toilets; interpretive signs
Best Time To Visit: Spring through fall when the main park road is open. Morning light highlights the steam and mud; avoid midday glare. To dodge crowds in peak summer, arrive before 9am or after 3:30pm.
Tips Advice: Stay on the boardwalks at all times; the ground is hot and chemically aggressive.
Carry water; no potable water spigots are noted here.
Bison are common—keep 25 yards from all wildlife, 100 yards from bears and wolves.
The sulfur smell can irritate sensitive visitors; masks help.
Bear spray advisable when moving beyond the immediate boardwalk zones; cell service is unreliable.
Insider Tips: Arrive before 9am or after 3:30pm to beat crowds
Keep to the boardwalk; ground is hot and chemically aggressive
Bison are common—give space; carry bear spray if venturing beyond the boardwalk
Dragon's Mouth Spring is accessible via a short spur; the sulfur smell can be strong
Dawn and dusk offer dramatic lighting and wildlife activity

More details

Park Area: Hayden Valley
Family Friendly Notes: Boardwalks keep kids safe; be mindful of hot ground and sulfur vents
Attraction Type: Mudpot/Hydrothermal Area
Elevation Feet: 7813
Distance From Entrance: 5.8 miles north of Fishing Bridge Junction; 9.7 miles south of Canyon Junction
Accessibility Level: Drive-up view with boardwalks; lower loop wheelchair accessible; northern part paved but steep with stairs at the northern end.
How To Get There: From Grand Loop Road, turn into the Mud Volcano parking area on the west side; follow boardwalks to Mud Volcano, Sulfur Caldron, and Dragon's Mouth Spring.
Parking Availability: Nearly 70 spots; can fill up, but openings occur as visits end.
Road Type: Paved trails with boardwalks; accessible routes along the lower loop
Seasonal Access: Spring, summer, and fall when the main park road is open.
Entry Fees: Varies; park entrance fees apply
Main Features: Mudpot, Sulfur Caldron, Dragon's Mouth Spring, fumaroles
What Youll See: Boardwalks and overlooks; bubbling mudpots, steaming vents, sulfur-stained rock, and Dragon's Mouth Spring adjacent to the road.
Unique Characteristics: Located near the Yellowstone Caldera's resurgent dome; highly acidic hydrothermal chemistry; active mud production fueled by subterranean gases
Safety Considerations: Chemistry: highly acidic waters and toxic gases; Temperature: surface ground can exceed 200°F; Gravity: uneven boardwalks; Wildlife: keep distance from large mammals; Do not leave the boardwalk
Best Viewpoints: Mud Volcano overlook; Sulfur Caldron overlook across the road; Dragon's Mouth Spring overlook
Photo Opportunities: Steam plumes at dawn; close-up bubbling mud; sulfur-stained crusts with morning light
Photography Spots: Overlooks for Mud Volcano and Sulfur Caldron; Dragon's Mouth Spring plumes
Stargazing Quality: Moderate
Sunrise Sunset Quality: Alpenglow possible; steam visible with sunrise
Visitor Center Present: 0
Restrooms Available: 1
Restroom Type: Vault toilets; accessible restrooms
Picnic Areas: 0
Interpretive Signs: 1
Cell Service: Unreliable; expect patchy coverage
Water Available: 0
Guided Tours Available: 0
Trailheads Here: Mud Volcano Trailhead; Dragon's Mouth Spur
Connecting Trails: Mud Volcano Loop; Dragon's Mouth Spur; Lower Loop
Nearby Services: Parking; vault toilets; interpretive signs; bring water
Common Wildlife: Bison; elk; coyotes; grizzly bears; wolves
Best Wildlife Times: Bison commonly near boardwalks and parking; dawn and dusk for broader wildlife
Fall Colors Peak: Late September–October
Geological Formation Type: Mudpot/Hydrothermal Area
Scientific Interest: Proximity to resurgent dome; ongoing ground deformation within the caldera; extremophile microbes in acidic waters
Road Opening Dates: Spring through fall; check park alerts for closures
Snow Lingering: Lingering into spring; check park updates for snow conditions
Winter Access: Limited; most boardwalks not maintained for winter travel; road status varies
Best Visit Times: Early morning or late afternoon to avoid crowds; spring through fall for open roads
Best Season: Spring through fall
Weather Patterns: Thermal area; sulfur odors; variable weather; can be windy near Hayden Valley
Peak Fill Times: Parking tends to fill in mornings during peak season; best to arrive before 9am
Busiest Season: Summer (July–August)
Fishing Nearby: 0
Swimming Allowed: 0
Boating Allowed: 0
Climbing Areas: 0
Review Summary: Mud Volcano presents a dynamic, close-up look at Yellowstone's geothermal system. The boardwalks provide safe access to bubbling mud and steam, while the sulfur air and heat remind you of the park's volcanic heart. Parking can be competitive in peak season, so plan timing accordingly.

Location

Photos

Dragon's Mouth Spring at Mud Volcano in Yellowstone National Park, a wooden sign set on sandy ground with pines and blue sky.

Mud Volcano at Yellowstone National Park emits steam over vivid mineral pools and muddy terrain.

Mud Volcano pool at Yellowstone National Park showing a steaming blue-green pool surrounded by mineral terraces and grasses under a clear sky.

Mud Volcano information panel at Yellowstone National Park explains steaming mud pools and explosive terrain in the Mud Volcano area.

Frequently asked questions

Do I really need to arrive before 9am to get parking?

Yes. The Mud Volcano lot holds ~70 spots and fills quickly in peak season; arriving before 9am or after 3:30pm helps secure a space.

Is it worth the 0.6–0.85 mile loop to see Mud Volcano and Dragon's Mouth Spring?

Yes. The short loop exposes bubbling mudpots, steaming vents, and the dramatic Dragon's Mouth Spring; the boardwalks keep you safe while you observe the chemistry in action.

Can I walk off the boardwalk to get closer to the mud?

No. Leaving the boardwalk endangers you and damages the delicate hydrothermal ground; stay on the designated paths.

Will I see bears or bison here?

Bison are common around Mud Volcano; maintain 25 yards from all wildlife, and 100 yards from bears and wolves.

Is there potable water nearby?

Potable water spigots aren’t noted at Mud Volcano; bring water from elsewhere in the park.