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West Thumb Geyser Basin - Yellowstone National Park

On the west thumb of Yellowstone Lake, this trail/boardwalk makes a loop and passes several hot springs and pools.
Rating: 5 out of 5 by EveryTrail members
Difficulty: Easy
Length: 0.7 miles
Duration: Less than 1 hour
Family Friendly

Overview :  Lake Facts

Elevation: 7,733 ft (2,357 m)
Area: 131.7 sq mi (341 sq km)
Shoreline: 141 mi (227 km)
Width: 14 mi (23 km)
Length: 20 mi ... more »

Tips:  Hydrothermal features are fragile rarities of nature. Yellowstone preserves the largest collection of hydrothermal features on the... more »

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Points of Interest

1. Fumaroles

2. Twin Geysers

Twin Geysers—one geyser with two vents—has short periods of dramatic eruptions and extended periods of dormancy. After a 23-year dormancy, it began erupting again in 1998; its last known eruption was in 1999. Visitors lucky enough to witness an eruption see a two-part event. The west vent erupts 70 feet (21 meters), then the east vent erupts more ... More

3. Abyss Pool

One of the deeper hot springs in the park, Abyss Pool descends to 53 feet (16 meters). It varies from turquoise blue to emerald green to various shades of brown. In 1883, a park visitor described it as "a great, pure, sparkling sapphire rippling with heat."

4. Black Pool

Not long ago, Black Pool really was black. Lower water temperature allowed thick mats of dark green and brown thermophiles (heat-loving microorganisms) to grow in the pool, causing it to appear black. The water temperature rose during the summer of 1991, killing these organisms. Black Pool also erupted that summer and several times the following... More

5. Big Cone

Jutting out into Lake Yellowstone, Big Cone, a companion to Fishing Cone, is a large sinter cone, and is sometimes seen completely submerged by the lake. Eruptions from this geyser are rare, and only reach heights of one foot or less.

6. Fishing Cone

Mountain men told of a geyser on the shore of a high alpine lake where one could catch a trout, swing the pole around, dip it into the boiling pool, and cook the fish without taking it off the line. This cooking-on-the-hook feat at Fishing Cone became famous after it was described by a member of the 1870 Washburn Expedition. Visitors often dressed... More

7. Lakeshore Geyser

Accounts from the 1920s and 1930s tell of Lakeshore Geyser erupting up to 50 feet (15 meters). The smaller of the two geyser vents is generally not exposed until mid to late August. Although Lakeshore Geyser boils vigorously and almost continuously, and often erupts a few feet, its last known major eruption was in 1970. One day, however,... More

8. Lakeside Spring

Lakeside Spring's blue-green pool of thermal water drains into Yellowstone Lake. The colors you see in the pools of West Thumb are created, in part, by what grows in these hot waters. Thermophiles (heat-loving microorganisms) have different colors and different temperature requirements. Generally, green and brown indicate organisms living in... More

9. Seismograph and Bluebell Pools

These pools used to be known as the "Blue Pools." After the 1959 Hebgen Lake earthquake, which measured 7.5 on the Richter scale, the pools were renamed. At West Thumb, no one recorded the nature of the changes caused by the quake, but perhaps someone thought Seismograph Pool somehow "registered" the earthquakes. (A seismograph measures the... More

10. Thumb Paint Pots

Known today as the Thumb Paint Pots, the Hayden Expedition of 1871 originally named these fanciful features the "Mud Puffs." Picture a field of miniature mud volcanoes that are 3 to 4 feet (1 meter) high with steam curling from their delicate mud chimneys in various shades of red. Surrounding the cones, the mud appears to be stirred and mixed to... More

11. Surging Spring

Surging Spring is true to its name. With an average temperature of 167 degrees Farenheit (75 degrees Celsius), it domes up and overflows, sending waves of water surging into the lake.

12. Collapsing Pool

Collapsing Pool, for obvious reasons, was also named for its appearance. Like Ledge Spring, this pool can sometimes be seen full and blue, or colorful and half empty.

13. Ledge Spring

Named for its appearance, Ledge Spring fluctuates from hot, blue, and overflowing to cool, colorful, and half empty.

14. Percolating Spring

When it was named, Percolating Spring bubbled vigorously like a coffee pot.

Thumb Geyser is now totally inactive and lies covered by the cool runoff of other springs like these in the middle of the geyser basin. "Dynamic" describes any geyser basin, but particularly the central area of West Thumb. These features are constantly in flux, changing from season to season—even month to month.

16. Perforated Pool

Perforated Pool is one of a group of hot springs in the middle area of the basin that all seem to share a common plumbing system. When major features, such as Abyss and Black pools, are in an active phase, this secondary cluster can be drained of water.

17. Ephedra Spring

Ephedra Spring, like many of the hot springs in the Central Basin of West Thumb, can vary dramatically in appearance depending on how hot or cool it is, and how much water it contains.

18. Blue Funnel Spring

Blue Funnel Spring was long known for the distinctive ring of color around its perimeter. However, when Abyss pool began erupting during the winter of 1991-92, the water in Blue Funnel, and in adjacent Perforated Pool and Ephedra Spring, cooled and sank well below the rim. Then the four features appeared to exchange energy: Abyss stopped erupting ... More