Yellowstone became the world's first national park in 1872 when it was established, in large part, to preserve the weird and wonderful hydrothermal features that dot its vast landscapes. Nowhere else on the planet can equal the dazzling diversity and density of Yellowstone's geysers, mudpots, fumaroles, and hot springs.

An easy, one-mile hike makes a loop through this small but splendid basin. The mudpots and springs here at the base of Paintpot Hill range in color from gray and white to deeper blues and greens, fringed in spots with vibrant reds and oranges. The basin boasts an active geyser, too: Blood Geyser, which has steady and constant activity rather than erupting at intervals. Though these features are just a short walk from a road, their location makes them a good spot to get away from larger crowds.

Yellowstone’s largest geyser basin spreads across a wide plain bisected by the Firehole River. Hundreds of pools, fumaroles, mudpots, and geysers dot the landscape, arranged in clusters with evocative names like the Quagmire Group and the Kaleidoscope Group. A boardwalk meanders through the Fountain Paint Pots with close-up views of geysers and mudpots, while the Firehole Lake Drive makes a scenic loop past bubbling pools and steaming vents.

A half-mile boardwalk features two of Yellowstone’s largest hot springs: Grand Prismatic Spring and Excelsior Geyser Crater. Grand Prismatic is the largest hot spring in the park, 330 feet in diameter at its widest and 121 feet deep. Views from ground level are easier to access, but the immensity of this pool is best appreciated from a higher angle. A ⅔-mile hike from the Fairy Falls Trailhead leads to an overlook across the basin, where the vibrant colors of Grand Prismatic are fully revealed.

Mudpots roil and seethe on a hillside above the Yellowstone River, filling the air with the pungent fumes of sulphuric acid. This is an active landscape, a collection of resurgent domes at the convergence of multiple faults, and the bubbling springs of dissolved clay belie the extreme forces at work on the rocks and soil here.

This large thermal area is home to the world’s largest active geyser: Steamboat Geyser. During rare and unpredictable eruptions, Steamboat shoots superheated water more than 300 feet into the air. But even when Steamboat isn’t erupting, Norris is a wonderland of geothermal features. Boardwalks wind through open flats and lodgepole pine woodlands, providing splendid views in an area that’s been geothermally active for at least 115,000 years.

Old Faithful, the world’s most famous geyser, is found here in Yellowstone’s most popular thermal area. Check out the geyser prediction board in the Visitor Center to make sure you don’t miss the next eruption, then take a stroll along the boardwalks and trails through the world’s most densely-concentrated collection of geysers. A sunset walk along the Firehole River, with steam rising through the silhouetted lodgepoles beneath a sky with colors that rival the hot springs, is simply sublime.

Nearly a mile of boardwalks loop through this impressive array of geysers and hot springs on the shores of Yellowstone Lake. Though polychromatic pools bubble and steam here, the area’s best-known feature is Fishing Cone – a geyser just offshore. Here, early park visitors were fond of catching a fish in the cool waters of the lake before “cooking-on-the-hook” by dropping it into the cone.