Ear Spring, Hot spring in Upper Geyser Basin, Yellowstone National Park, US

This hot spring is located in the Upper Geyser Basin of Yellowstone National Park with water temperatures exceeding 93°C (198°F). It sits near Old Faithful amid numerous other geothermal features that define the landscape.

The spring experienced a major eruption in 2018 that shot water 9 meters (30 feet) high and released items visitors had deposited over many decades. This event showed how dynamic and unpredictable the geothermal activity in this area can be.

The name Ear Spring refers to the pool's outline, which resembles a human ear. The feature sits in the Upper Geyser Basin close to Old Faithful, and its shape is visible from the boardwalk that passes it.

Visitors reach the spring by following designated wooden boardwalks through the Upper Geyser Basin that maintain safe distances from the scalding waters. The paths are clearly marked, but the water is extremely hot and the ground can be slippery, especially in wet conditions.

During the September 15, 2018 eruption, which lasted about a minute and reached 20 to 30 feet, the spring threw out small rocks and trash people had dropped in over the years. The heated water killed the surrounding bacterial mats that normally grow in cooler conditions. A new thermal feature then opened under the boardwalk near Pump Geyser, spouting water the night of September 18–19, 2018, and the National Park Service temporarily closed that section.