Castle Geyser, Yellowstone: 80-ft sinter cone on a 0.25-mile boardwalk

Castle Geyser erupts steam and mineral-white deposits in Yellowstone National Park's Upper Geyser Basin.

A white geyserite cone rises beside the boardwalk, steam lifting in the spray during eruptions. That cone forms from mineral-rich water that precipitates geyserite as it erupts, driven by magma 3–8 miles underground. The cone’s age is about 1,000 years, with the surrounding sinter shield dating around 10,000 years and terraces potentially forming over 200,000 years. Eruptions reach up to 90 feet and last about 20 minutes of water, followed by a 30–40 minute steam phase.

Access & viewing

GPS Coordinates: 44°27′48″N 110°50′12″W
Accessibility: Boardwalks with gentle slopes; some incline areas near viewing points

Conditions & safety

Permits Required: 0

Planning advice

Nearby Attractions: Old Faithful, Upper Geyser Basin, Old Faithful Inn
Nearby Facilities: Old Faithful Visitor Education Center; restrooms; drinking water spigots
Best Time To Visit: Accessible year-round; aim for golden hours when spray can create rainbows and crowds are lighter. Avoid midday glare and peak crowds by choosing early morning or late afternoon.
Tips Advice: Observe during golden hour for rainbow spray.
Stay on boardwalks; extremely hot water and steam in the vicinity.
From Old Faithful, the Castle Geyser walk is ~0.2 miles one-way.
Dress in layers; weather can change rapidly.
Insider Tips: Rainbow spray is most vivid in the morning light
The short 0.2-mile walk from Old Faithful is worth the view
Check eruption timing but be prepared for variability
Do not touch the water or sinter surfaces

More details

Park Area: Upper Geyser Basin, Yellowstone National Park
Family Friendly Notes: Keep children within arm’s reach near Castle Geyser. Stay on the boardwalks and the designated viewing paths, because the ground around the cone is hot and unstable and steam can be strong during eruptions. Wear sturdy shoes and supervise young visitors at all times.
Attraction Type: Thermal Feature
Elevation Feet: 7333
Distance From Entrance: 0.2 miles one-way from Old Faithful
Accessibility Level: Drive-up view with boardwalk access; mostly accessible
How To Get There: Park near Old Faithful; follow the Upper Geyser Basin boardwalks toward Castle Geyser for a short 0.2-mile stroll.
Parking Availability: Parking near Old Faithful; can fill quickly during peak times
Road Type: Paved park roads; viewing via maintained boardwalks
Seasonal Access: Accessible year-round during park operating hours
Entry Fees: Varies
Main Features: Geyserite cone (~12 ft tall) with a ~3 ft orifice; large sinter shield; eruption height up to 90 ft; water phase ~20 min, steam ~30–40 min
What Youll See: A stark white cone formed by mineral deposits, with bursts of spray and steam; boardwalks encircle the feature and provide close viewing near Old Faithful
Unique Characteristics: One of Yellowstone’s largest ancient geyserite cones; sinter terraces beneath the cone may have formed over up to 200,000 years; among the park’s oldest active geysers
Safety Considerations: Thermal hazard: extremely hot water and steam; keep a safe distance from the vent area. Gravity: Yellowstone terrain is uneven—stay on boardwalks. Chemistry: mineral-rich water can be corrosive; do not touch or ingest. Weather can shift quickly; dress in layers and protect against sun.
Best Viewpoints: Stand along the Castle Geyser circle on the Upper Geyser Basin boardwalks for frontal views of eruptions
Photo Opportunities: Golden-hour spray halos; close-up of the cone with dramatic steam plumes; backlit eruptions from vantage points along the boardwalk
Photography Spots: East-facing vantage during sunrise for backlit spray; front-on shots along the main boardwalk loop
Stargazing Quality: Excellent under dark skies when not crowded
Sunrise Sunset Quality: Alpenglow potential; sun angles enhance the spray at certain times
Visitor Center Present: 1
Restrooms Available: 1
Restroom Type: Restrooms are available in the Old Faithful area.
Picnic Areas: 0
Interpretive Signs: 1
Cell Service: Spotty in the basin; plan offline maps
Water Available: 1
Guided Tours Available: 0
Trailheads Here: Old Faithful – Castle Geyser link via Upper Geyser Basin boardwalks
Connecting Trails: Boardwalk network connects Castle Geyser with Old Faithful viewing areas
Nearby Services: Old Faithful Village amenities; Old Faithful Visitor Education Center; restrooms; potable water spigots
Common Wildlife: Bison, elk; bears in the broader area; keep distance and follow bear-safety rules
Best Wildlife Times: Dawn and dusk when animals are most active
Geological Formation Type: Cone geyser
Scientific Interest: Ancient geyserite cone; large sinter shield; long-term formation of geyserite terraces; active hydrothermal system linked to shallow magma
Winter Access: Limited winter access; check park updates for road status
Best Visit Times: Early morning or late afternoon to minimize crowds and catch optimal light on spray
Best Season: Year-round; shoulder seasons recommended for lighter crowds
Weather Patterns: Possible afternoon thunderstorms; rapid weather shifts; wind direction influences spray visibility
Peak Fill Times: Parking capacity tends to fill quickly during peak seasons; plan to arrive early
Busiest Season: Summer (June–August)
Fishing Nearby: 0
Swimming Allowed: 0
Boating Allowed: 0
Climbing Areas: 0
Review Summary: Rated highly (4.9 stars from 176 reviews) for proximity and scale of the cone, with visitors appreciating the reliable eruption show and safe boardwalk viewing. Expect crowds during peak times but the short access from Old Faithful keeps the experience efficient.