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West Thumb Geyser Basin -
Yellowstone National Park

This peninsula was originally named “West Thumb” by the 1870 Washburn Party. It was later dubbed “West Arm” by the Hayden Survey, followed by West Bay” on the Norris map, and later “West Bay or Thumb.” While attempts were made in the 1930s to change the name back to “West Arm”, it ultimately failed and “West Thumb” is now the accepted name.


  • West Thumb Geyser Basin & Boardwalk: West Thumb is located on the western part of the bay, next to the lake, and the West Thumb Geyser Basin is the largest geyser basin on the shores of Yellowstone Lake. West Thumb bay was formed by a large volcanic explosion that occurred approximately 150,000 years ago, resulting in a collapsed volcano, called a caldera, that eventually filled with water forming this bay and an extension of Yellowstone Lake. Far beneath the earth’s surface, a magma chamber bulged up, cracked, and released the magma providing the source of heat for the West Thumb Geyer Basin.


An extensive boardwalk of mostly level terrain with a few inclines and declines provides for an enjoyable and wheelchair accessible path around the many hydrothermal features along the bay’s shore. Lookout platforms along the boardwalk provide easy and up-close viewing of the basin’s paint pots, hot springs, geysers and cones, and beautiful emerald pools. Several features extend out into the bay, including the famous Fishing Cone, a unique cone-shaped hydrothermal feature popping up out of the lake. In the past, it was a location where fish that were caught in the lake, could immediately be hoisted to and dipped in the cone to be cooked in the hot water.

Along the shoreline of West Thumb are several Native American hearth sites, or remnants of ancient living and camping areas, and locations of food gathering.

  • Information Station: The structure that is the Information Station was built in 1925 and serves as a Ranger Station and a Yellowstone Forever store/sales outlet. In the summer months, it also provides the meeting location for interpretive walks and talks. During the winter months, it serves as the West Thumb Warming Hut. Friendly and helpful staff are available to answer questions.

  • West Thumb Parking Lot & Picnic Area: There is a large parking area with a picnic area at the eastern edge of the parking lot. Several picnic tables are well shaded by large pine trees. Five restrooms are available at this location. 

  • Lake Overlook Trailhead: This trail begins at the West Thumb parking lot. It is a two-mile out-and-back loop hike through a sparse pine forest, then some meadows as you approach the top of a hill. The loop junction begins after crossing the South Entrance road and has an approximate 250-foot gain in elevation. At the summit, you will find a wooden bench to rest and take in a panoramic view of the West Thumb area. There are also a few small geothermal hot pools and vents in the area.

  • Duck Lake Trailhead: This trailhead is also located at the west side of the West Thumb parking area and is a short .4-mile (.8-mile round trip) to Duck Lake. The trail has a gentle climb of fewer than 100 feet before it drops downward about 90 feet to the lake. Duck Lake covers 37 acres, has a maximum depth of 60 feet, and is surrounded by forest. It also has some fun beaches to play on. The lake is the result of an ancient volcanic explosion crater. This is the same lake that can also be seen along the Old Faithful to West Thumb road just before the junction to West Thumb.

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