Outside says the Grand Prismatic Spring is Yellowstone's most photographed thermal feature.
Superheated springs attract thermophiles, which thrive in hot settings. Thermophile means heat loving. The hardiest thermophiles thrive in colourless or yellow water, whereas orange, brown, and green live at the spring's edge.
Wadi Rum is a 277-square-mile (717-square-kilometer) desert in South Jordan. You might imagine you're on Mars while exploring the spectacular wilderness. Wadi Rum has mile-high sandy valleys, red dunes, and stunning rock formations.
Thomas Edward Lawrence was a British liaison officer during the Arab Revolt against the Ottoman Turks. Wadi Rum Nomads says he called it "huge, reverberating, and God-like."
Vatnajokull glacier is Europe's second-largest. It covers 3,130 square miles (8,100 square kilometres), approximately 8% of Iceland's surface.
The glacier is nearly 900 metres deep in some areas and hides active volcanoes, including Grmsvötn, raefajökull, and Bárarbunga. Geologists say this region's volcanoes are overdue and could erupt within 50 years.
New Zealand's glowworm tunnels offer an alternative to stargazing.
NewZealand.com says the Waitomo Caves have the best glowworms in New Zealand. Take a canoe, kayak, or walk into the Waitomo Caves to see the glowworms. Strange creatures light the road like stars in a sci-fi movie in this peculiar habitat.
Salar de Uyuni in Bolivia is the world's largest salt flat, covering 10,000 square kilometres. The huge salt flat is visible from space.
The salt flat's middle is 10 metres deep. Salar de Uyuni has 10 billion tonnes of salt, according to Salardeuyuni.com. 70% of the world's lithium reserves reside under the salt flat.
Sossusvlei's crimson dunes are among the world's tallest, reaching approximately 400 m. They're one of Namibia's top attractions.
Namib-Naukluft National Park has a Martian-like environment. Sossusvlei means "dead-end," referring to the dunes blocking the Tsauchab River.
Middle Island, Western Australia's Lake Hillier seems alien. The pink lake, Indian Ocean, and lush green forest are in stark contrast.
Scientists aren't sure how the lake got its pink colour, according to Hiller Lake. Dunaliella salina microalgae in the lake produce red carotenoids. Halophilic "salt-loving" bacteria may also have a role. A interaction between salt and sodium bicarbonate could also change the lake's colour.
Ethiopia's Danakil Depression is an unfriendly and foreign region. According to the BBC, the Danakil Depression is like standing on Venus (without the crushing atmosphere, of course). Sulphuric acid and chlorine permeate the air, while acid ponds and geysers dot the terrain.
According to the BBC, this location often reaches 113°F (45°C), making it one of the hottest places on Earth.
Lava from Hawaii's Kilauea volcano spews into the Pacific Ocean on the Big Island's south shore, generating dramatic views.
According to Go Hawaii, Kilauea is an active volcano. It's 45 miles (72 km) southwest of Hilo in Hawaii Volcanoes National Park.
Pamukkale, Turkey's "Cotton Castle," has mineral pools surrounded by white "cotton-like" shelves and ridges.
A calcium bicarbonate-rich spring flowed over a cliff and formed the distinctive scene. According to Turkey's Ministry of Culture and Tourism, water leaves behind white calcium deposits.
Rainbow Mountain is in Peru's Andes Mountains, around 5,200 m above sea level. Different mineral deposits form the mountain's technicolour look.
This Andean rainbow treasure was concealed under snow until recently. As the snow melted, the hidden jewel was uncovered, and hundreds visit daily.