Ear Spring

Ear Spring, located in the Upper Geyser Basin of Yellowstone National Park, is one of the park’s most intriguing and dynamic hot springs—famous not only for its unusual ear-like shape but also for its rare and dramatic eruptions. At first glance, it may seem calm and deceptively simple, a gently steaming blue pool nestled among sinter formations, but beneath its placid surface lies a powerful geothermal system that occasionally reminds visitors of the tremendous energy flowing just below the ground.

Ear Spring

Quick Reference: Ear Spring

Feature	Details
Name	Ear Spring
Location	Upper Geyser Basin, Yellowstone National Park, Wyoming, USA
Type	Hot Spring
Shape Origin	Named for its ear-like shape resembling a human ear
Temperature	Average 197.1°F (91.7°C); often above boiling point (198°F / 92°C at elevation)
pH Level	Average 8.4 (slightly alkaline)
Conductivity	Average 1889 µS/cm
Eruption Frequency	Very rare; last major eruption on September 15, 2018
Notable Eruption Event	2018 eruption ejected old coins, cans, a baby pacifier, and other debris from the vent
Appearance	Deep blue water with ivory-white sinter edges and constant steam emission
Formation Type	True hot spring heated by underground hydrothermal system
Nearby Features	Old Faithful, Doublet Pool, and Blue Star Spring in the Upper Geyser Basin
Elevation	Approximately 7,375 feet (2,248 meters)
Best Viewing Time	Early morning or late afternoon when steam is visible in cooler air
Accessibility	Easily accessible via the Upper Geyser Basin boardwalk
Safety Note	Stay on designated boardwalks; surface water is extremely hot and fragile
Fun Fact	The 2018 eruption revealed decades of human debris, showing why nothing should be thrown into geothermal features

True to its name, Ear Spring is shaped somewhat like a human ear, with curved edges and a narrow opening that gives it its distinctive appearance. The pool’s surface water is extraordinarily hot—often above the boiling point of 198°F (92°C) at Yellowstone’s elevation. This extreme temperature makes Ear Spring a true hot spring, continuously venting steam and heat while keeping its water crystal clear and deep blue due to the lack of microbial life that can survive such heat. Over time, the edges of the pool have been coated in delicate sinter deposits, giving it a smooth, ivory-like border that glistens in the sunlight.

Although it appears calm most of the time, Ear Spring is also capable of erupting—an event that happens only rarely but with impressive force. Its last recorded eruption occurred on September 15, 2018, marking the first significant activity in 14 years. This eruption became one of the most memorable in Yellowstone’s recent history, not for its height or duration, but for what it revealed. Along with the usual boiling water and steam, the spring ejected a startling collection of debris—old coins, cans, a cement block, and even a baby pacifier—objects that had been tossed into the spring over decades. This historic event served as a powerful reminder that Yellowstone’s thermal features are alive and unpredictable, and that throwing objects into them can have lasting consequences. Many items found were from the park’s earlier years, a fascinating but sobering glimpse into human carelessness and the resilience of nature.

Scientifically, Ear Spring offers a window into Yellowstone’s geothermal complexity. It maintains an average temperature of 197.1°F (91.7°C), an average pH of 8.4, and an average conductivity of 1889 µS/cm, reflecting its mineral-rich, alkaline nature. The spring is connected to the same deep hydrothermal system that fuels nearby features such as Old Faithful and Grand Geyser. Its water percolates through underground fractures, heating as it comes into contact with magma-heated rock before emerging at the surface. When subsurface pressure builds, eruptions can occur, clearing out blockages and resetting the spring’s natural balance.

For visitors walking along the Upper Geyser Basin boardwalk, Ear Spring is an unassuming yet captivating stop—its glassy blue waters shimmering with heat, a soft mist rising from the vent, and an ever-present hum of geothermal activity. Despite its beauty, it demands respect. Park scientists emphasize the importance of staying on the boardwalks and never disturbing geothermal features, as even minor interferences can disrupt the delicate underground systems that sustain them.