Firehole Spring, Lower Geyser Basin, Yellowstone National Park

Firehole Spring, located along Firehole Lake Drive in Yellowstone National Park's Lower Geyser Basin. The spring is characterized by a thumping behavior that is caused by the implosion of bubbles rising from the base of the pool due to changing temperature and pressure conditions within the pool.  The bubbles can be seen in this picture as the whitish mass in the center of the pool.  USGS photo by Mike Poland, September 5, 2024.