The World’s Most Punctual Natural Wonder Lives Up to Its Name in Wyoming’s Volcanic Caldera

Old Faithful, Yellowstone National Park

Old Faithful puts on over 5,000 shows a year. Beneath the crowds and gift shops, ancient volcanic forces heat underground reservoirs until pressure builds and – right on schedule – thousands of gallons of 204°F water blast skyward.

But there’s more to this geyser than its amazing clockwork show.

It’s so faithful, its eruption can be predicted to the minute

Old Faithful got its name in 1870 when Nathanial Langford noticed how regularly it erupted during the Washburn expedition.

Its intervals have grown from 66 minutes in 1939 to about 94 minutes today. Park rangers can predict eruptions with 90% accuracy within 10 minutes by measuring how long the previous eruption lasted.

Short eruptions (under 2.5 minutes) lead to waits around 65 minutes, while longer ones mean 91-minute waits. The shortest wait ever was 34 minutes back in 2000, and the longest was 125 minutes. You can check when the next eruption will happen at the visitor center or on the Yellowstone app.

Earthquakes have permanently changed how Old Faithful erupts

The 1959 Hebgen Lake earthquake (7.3 magnitude) cut daily eruptions from 21 to 20. The 1975 Norris Geyser Basin earthquake (6.1 magnitude) stretched the wait times even more. Most dramatically, the 1983 Borah Peak earthquake (6.9 magnitude) made the average wait jump from 69 to 77 minutes in just four months.

These changes happened suddenly after each earthquake, not gradually. Scientists think these quakes changed the underground plumbing that feeds the geyser, affecting how water flows through.

Heat-loving microbes live in the scalding water

Scientists found a thriving community of tiny organisms inside Old Faithful in 2023. Thermocrinis ruber bacteria make up over 60% of these microbes. They survive in water as hot as 195°F and turn carbon dioxide from the geyser into energy.

These tough little bacteria create protective films on the channel walls to survive being shot 130 feet into the air every 90 minutes.

Researchers found more genetic variety in Old Faithful’s Thermocrinis strains than in any non-erupting hot spring in Yellowstone. Other heat-loving microbes include Thermus aquaticus and Pyrobaculum species.

Early visitors used Old Faithful as a washing machine

Back in 1877, explorer Frank D. Carpenter wrote about how his group put dirty clothes in pillowcases and threw them into Old Faithful’s opening. When the geyser erupted, their laundry shot over 100 feet up and came back perfectly cleaned by the hot, churning water.

They also experimented by tossing “at least a thousand pounds” of rocks, trees and stumps into the vent to see if the geyser could push them out. Soldiers stationed in the park kept doing this until the early 1900s.

Park officials eventually banned this harmful practice when they realized it was damaging the geyser’s underground system.

Native Americans weren’t afraid of the geysers

Despite myths spread by early park officials, Native Americans weren’t scared of Yellowstone’s geysers. Archaeologists have found hundreds of campsites near thermal features dating back 11,000 years. The Shoshone tribe used hot springs to soften bighorn sheep horns before reshaping them into bows.

Crow tribe members called geysers “bide-mahpe” (sacred water) and saw them as places with great healing powers. According to Crow legend, a hunter named Old Woman’s Grandchild created some geysers after killing animals that turned into thermal features.

Tribes like the Blackfeet, Flathead, Bannock, and Nez Perce called Yellowstone “land of the geysers” or “place of hot water.”

Trash thrown in geysers can pop up decades later

In 2018, Ear Spring geyser near Old Faithful erupted for the first time in 60 years, spitting out items from as far back as the 1930s.

The junk included an old pacifier, coins, cans, cigarette butts, and even a piece of cinder block. Throughout Yellowstone’s history, tourists have tossed everything from horseshoes to couches into thermal features.

Morning Glory Pool got so full of trash people nicknamed it “Garbage Can.” During a cleanup in 1950, workers pulled out 76 handkerchiefs, bath towels, socks, and $94.37 in coins.

These foreign objects harm geysers by clogging their natural plumbing and changing water chemistry. If you throw items into thermal features now, you could face fines up to $5,000.

Scientists use geyser microbes to hunt for alien life

Researchers study Old Faithful’s tough microbes to understand how life might exist on other planets. In 2023, scientist Lisa M. Keller collected water samples during eruptions using weighted sterile containers placed near the geyser.

When kept at temperatures matching Old Faithful (70-90°C), the microbes immediately showed signs of life.

NASA scientists apply these findings to Saturn’s moon Enceladus and Jupiter’s moon Europa, which both show signs of geyser activity. The methods created to find life in Earth’s geysers could help future space missions.

Researchers think similar tiny organisms might live in the water plumes shooting from Enceladus’s underground ocean.

Water in Old Faithful reaches 244°F without boiling

Old Faithful’s underground reservoir holds water at 244°F, much hotter than water’s normal boiling point of 212°F. This super-hot state is possible because the water is under intense pressure underground, keeping it liquid despite extreme heat.

Between 1983 and 1994, scientists lowered four probes with temperature sensors and video cameras into the geyser’s opening, reaching 72 feet down.

They recorded incoming super-hot steam reaching 265°F. When pressure drops as water rises through the narrow channel, the super-hot water instantly boils into steam, creating the explosive eruption.

Each eruption shoots out between 3,700 and 8,400 gallons of water in just 1.5 to 5 minutes.

Rain affects how often the geyser erupts

Research shows that rainfall directly influences Old Faithful’s schedule. During wetter years, the time between eruptions gets slightly shorter.

Since geysers run on groundwater flowing through underground chambers, more rain means more water for the system.

The effect is small but measurable—perhaps 1-3 minutes difference in average wait times between very dry and very wet years. Climate change models suggest this connection might become more noticeable in coming decades as rainfall patterns change in the Yellowstone region.

Old Faithful has its own private “plumbing system”

Unlike most hot springs in Yellowstone, Old Faithful isn’t connected to other geysers in the Upper Geyser Basin. This isolation is why it’s more reliable than other geysers. When scientists put harmless dye tracers into nearby features, none showed up in Old Faithful’s eruptions.

The geyser draws water from its own reservoir about 72 feet underground. Its cone stands 12 feet above the ground and is made of geyserite (silica deposits) built up over thousands of years.

The opening is about 2 feet across, widening to chambers below. This independent system means Old Faithful stays consistent while nearby features might change dramatically.

Steamboat Geyser is taller and bigger than Old Faithful

Even though Old Faithful is famous, it’s not the most impressive geyser in Yellowstone. Steamboat Geyser in the Norris Geyser Basin shoots water up to 300 feet high—almost twice as high as Old Faithful’s maximum of 185 feet.

Steamboat also releases three times more water during major eruptions (up to 25,000 gallons compared to Old Faithful’s 8,400 gallons).

However, you never know when Steamboat will erupt—it once stayed quiet for 50 years (1911-1961). Meanwhile, Old Faithful has erupted over 1 million documented times since people started keeping track.

This reliability is why 95% of park visitors see Old Faithful while very few ever witness Steamboat. Grand Geyser, also in the Upper Basin, is considered the tallest predictable geyser in the world.

Researchers use Old Faithful as a natural laboratory

Since 1938, when mathematician Harry Woodward first described how eruption length relates to wait times, Old Faithful has become one of the most studied natural features on Earth.

The geyser is watched 24/7 with equipment that detects pre-eruption tremors, cameras that measure water temperature changes, and sound sensors that listen to underground water movement.

In 2018, researchers placed 50 portable earthquake detectors around the geyser to create the first 3D map of its underground chambers. Between eruptions, tiny earthquake signals show water refilling the reservoir. Scientists also collect water samples after eruptions to study what’s in it, finding lots of silica, which forms the surrounding geyserite deposits.

Visiting Old Faithful in 2025

You’ll find Old Faithful in Yellowstone’s Upper Geyser Basin, 56 miles from the west entrance. Entry costs $35 per vehicle (good for 7 days) or it’s free with an America the Beautiful annual pass ($80).

The geyser erupts about 20 times daily between 6am and 10pm. You can check predicted eruption times at the visitor center or on the Yellowstone app.

Get there 20 minutes early to find good spots in the 300-seat viewing area.

There’s parking at the Old Faithful Visitor Education Center, but it fills up fast. Never step off the boardwalk—fines can reach $5,000 and might include jail time.