With its fluorescent natural wonders and diverse wildlife, Yellowstone National Park attracts 4.5 million visitors each year.

The world’s first national park was created on March 1, 1872, when President Ulysses S. Grant signed the Yellowstone National Park Protection Act. The law decreed that the headwaters of the Yellowstone River be “dedicated and set apart as a public park or pleasuring-ground for the benefit and enjoyment of the people.” The decision led to the creation of the National Park Service, which now protects more than 400 sites  across the United States.

What are Geysers?

Sprinkled amid the hot springs are the rarest fountains of all, the geysers. What makes geysers rare and distinguishes them from hot springs is that somewhere, usually near the surface in the plumbing system of a geyser, there are one or more constrictions.

Geysers are hot springs with constrictions in their plumbing, usually near the surface, that prevent water from circulating freely to the surface where heat would escape. The deepest circulating water of the system can exceed the surface boiling point of water (199°F/93°C). Surrounding pressure increases with depth, much as it does with depth in the ocean. Increased pressure exerted by the enormous weight of the overlying water and rock prevents the water from boiling. As the water rises due to heating, steam forms and expands, increasing pressure in the constricted plumbing near the surface. At a critical point, the confined bubbles actually lift the water above the surface vent, causing the geyser to splash or overflow. This decreases pressure on the system, and violent boiling results. Tremendous amounts of steam force water out of the vent, and an eruption begins. Water is expelled faster than it can enter back into the geyser’s plumbing system, and the heat and pressure gradually decrease. The eruption stops when the water reservoir is depleted or when the system cools.

There are more geysers in Yellowstone than anywhere else on Earth. Old Faithful, certainly the most famous geyser, is joined by numerous others big and small, named and unnamed. Though born of the same water and rock, what is enchanting is how differently they play in the sky. Riverside Geyser, in the Upper Geyser Basin, shoots at an angle across the Firehole River, often forming a rainbow in its mist. Castle Geyser erupts from a cone shaped like the ruins of some medieval fortress. Grand Geyser explodes in a series of powerful bursts, towering above the surrounding trees. Echinus Geyser spouts up and out to all sides like a fireworks display of water. And Steamboat Geyser, the largest in the world, pulsates like a massive steam engine in a rare, but remarkably memorable eruption, reaching heights of 300 to 400 feet.

Vastness of Yellowstone

While mostly in Wyoming, Yellowstone’s 2.2 million acres (8,900 square kilometers) extend into neighboring Idaho and Montana. The massive park covers an area larger than the U.S. states of Delaware and Rhode Island combined.

Yellowstone was established to protect an extraordinary collection of 10,000 thermal features, including geysers, hot springs, fumaroles and boiling mud pots created by underground volcanic activity. With 500 geysers, the park has more than half of all the world’s erupting hot springs.

While waiting for Old Faithful, the world’s most famous geyser, is a Yellowstone tradition, the park also boasts abundant wildlife viewing opportunities. With the largest concentration of mammals on the U.S. mainland, Yellowstone is home to bison — the U.S. national mammal — as well as black bears, bighorn sheep, deer, elk, moose and mountain goats.

You may also glimpse predators, such as one of the 1,000 grizzly bears known to inhabit the area, along with lynx, wolverines and wolves.

Bird lovers will relish the opportunity to see 300 species of birds. The park service provides a checklist for bird watchers hoping to spot them all.

While Yellowstone offers something in every season, services are limited from early November through late April. Bad weather can change road conditions at any time, so check operating dates  and conditions before visiting.

For those unable to visit, Yellowstone’s 10 webcams  offer glimpses of the park. So whether you’re planning to feel the mist from an Old Faithful eruption or looking for a brief virtual escape, Yellowstone offers an experience unlike any other. For the Silo, Jarrod Barker.

Featured image- Daphne Zheng via Getty Images