1: 1. The Door to Hell in Turkmenistan burns continuously for over 50 years.

2: 2. The Great Blue Hole in Belize is a giant marine sinkhole, perfect for diving.

3: 3. The Blood Falls in Antarctica features red water flowing from a glacier.

4: 4. The Salar de Uyuni in Bolivia is the world's largest salt flat.

5: 5. The Stone Forest in China is a surreal landscape of limestone pillars.

6: 6. The Fly Geyser in Nevada is a man-made geyser creating a colorful spectacle.

7: 7. The Mount Roraima in Venezuela inspired Sir Arthur Conan Doyle's "The Lost World."

8: 8. The Socotra Island in Yemen boasts unique flora and fauna found nowhere else.

9: 9. The Waitomo Glowworm Caves in New Zealand are illuminated by bioluminescent insects.