Iceland’s abundant geothermal energy heats the otherworldly, artificial lagoon of silica-rich water. One of Iceland’s most famous attractions, the Blue Lagoon is often a stop on a full-day tour of the top sites around Reykjavik, but it’s easy to while away half a day in the warm, steamy outdoor pools with their distinctive, milky hue. Although the lagoon might be artificial, that color is all-natural, the result of the sun’s reflection on silica in the water.

The turquoise water of UNESCO-listed Lake Louise mirrors a spectacular backdrop of summits in the Canadian Rocky Mountains. Snow-capped Mount Temple, Mount Whyte, and Mount Niblock frame the scene within Banff National Park, all visible from the 2.8-mile (4.5-kilometer), mostly flat Lake Louise Shoreline Trail that follows the northern shore. Most tours of Banff National Park stop at Lake Louise, along with other scenic highlights of the spectacular Icefields Parkway.

Measuring 984 feet (300 meters) across and plunging to a depth of 410 feet (125 meters), the Great Blue Hole is part of the UNESCO-listed Belize Barrier Reef System and is one of the world’s most spectacular places to scuba dive. (Jacques Cousteau even named it as one of his top 10.) Snorkelers can explore fringing reefs close to the surface of this dramatic natural feature, while divers will enjoy excellent visibility while descending along a wall of coral.

Ice-cold fresh water bubbles up from beneath the surface at Albania’s Blue Eye (Syri i Kaltër), a natural spring wrapped in oak and sycamore trees. Deeper water at the center of the pool creates a darker hue—some locals say it looks like the pupil of an intensely blue eye. No diver has ever reached the bottom of the pool, in part because intense upwelling makes downward swimming arduous.

When sunlight enters this Croatian sea cave just so, the interior glows a luminous azure color, while everything below the surface of the water turns a ghostly pink. It’s a phenomenon that’s most dramatic around noon on clear days—in those conditions, expect crowds at this popular spot. To visit the Bisevo Blue Cave (Modra Spilja), consider booking a boat tour that departs from Split, Hvar, or Vis, with the option to add stops at surrounding islands and seaside villages.

For most of the year, the largest salt flat on Earth stretches out in a perfect white sheet to the horizon. During the wetter months of December, January, and February, however, rainfall turns the Salar de Uyuni into a pristine mirror, creating surreal optical illusions that are the stuff of photographers’ dreams. The landscape is also home to the world's first salt hotel, Hotel Palacio de Sal.

Lake Pukaki (aka Turquoise Lake) is among the most photographed places … and for good reason. It has intensely blue water that offers a dramatic contrast to the snowy summit of nearby Aoraki/Mt. Cook, the highest mountain in New Zealand. The secret to the dramatic color? Finely ground rock dust left in the wake of retreating glaciers is suspended in the water, reflecting sunlight as it enters the water. Lake Pukaki is an included stop on many tours of Aoraki/Mt. Cook Village.

A highlight of Argentine Patagonia, the imposing-yet-accessible Perito Moreno Glacier is located in the country’s UNESCO-listed Los Glaciares National Park, and is part of the third-largest freshwater reserve on the planet. Milky-blue water surrounding Perito Moreno Glacier adds contrast to the glacier’s craggy edge; when the glacier sheds massive chunks of ice, they plunge into the lake with a thundering roar.

The Spanish name for the Marble Caves translates to “marble chapels,” and the natural formations do feel like a kind of sanctuary. Colorful layers in the calcium carbonate cliffs whorl into intricate designs reminiscent of marbled paper, forming a maze of brilliant stone suspended over the intensely blue waters of Lake General Carrera. These remote caves can only be accessed by boat, on tours following the lake’s intricate fringing of coves and inlets.

This azure lake in the crater of dormant volcano Mount Mazama is America’s deepest lake, with pristine water that goes to 1,949 feet (594 meters). Since no river feeds into the south-central Oregon lake, every drop comes from rain and melted snow. That means it’s one of the clearest and cleanest lakes on Earth, which only amplifies the dramatic hue. Crater Lake National Park is included in many multi-day tours of Oregon.