1. Hang Sơn Đoòng, Vietnam
Where better to start than the world’s largest cave? Hang Sơn Đoòng, which translates as mountain river cave, is in Vietnam’s Phong Nha Ke Bang National Park. The main cavern alone is 650 feet high and three miles long, while the rest of the cave stretches on for nine miles in total. Ceiling collapses have let in light, and that’s allowed some impressive verdant foliage to come to life in its depths – a pretty unique phenomenon. It even has its own weather system, clouds included, and the largest stalagmite known to man.
2. Blue Grotto, Capri
The beautiful Blue Grotto is a natural sea cave off the Italian island of Capri. Sunlight seeps into the 60 feet deep cave through an underwater cavity, giving it that enchanting glow. While swimming is off-limits, you can still explore the Blue Grotto by hopping on a tour where a rowing boat takes you inside. Whether or not you believe the local legends about its past (some say it was the swimming pool of Emperor Tiberius, others an abode to spirits and demons), you’re sure to be bewitched.
3. Saalfeld Fairy Grottoes, Germany
These German caves are known for their impressive colors, even declared the ‘most colorful grottoes in the world’ by the Guinness Book of Records. Once mined for shale, today they’re open to visitors, and one of the caverns is illuminated by lights to enhance the colors in the rock, which are caused by mineral deposits.
4. Shell Grotto, England
Margate’s Shell Grotto is something of an enigma. Decked floor-to-ceiling in shell mosaic, no one is sure when or why it was first created, only that it was discovered in 1835 and opened to tourists a few years later. There are plenty of fascinating theories to satisfy your inner Sherlock while you marvel at the ornate passageways.
5. Fingal’s Cave, Scotland
Fingal’s Cave is a Scottish natural wonder found on an uninhabited island off the south-west coast. What makes it such an extraordinary geological feat is the hexagonal columns of volcanic rock that surround its entrance, creating an incredible geometric pattern. Everyone from Queen Victoria to Pink Floyd has visited the cave, with the latter probably enjoying the natural acoustics it’s renowned for.
6. Škocjan Caves, Slovenia
See the biggest underground canyon in the world in the Škocjan Caves, a karst cave system that’s renowned as a natural gem with a place on the UNESCO World Heritage list. Carved out by the Reka River, the cave reaches 140m in height. The Cerkvenik Bridge crosses at one of the highest points – don’t look down if you’re scared of heights!
7. Mendenhall Ice Caves, Alaska
Even the journey to the Mendenhall Ice Caves in Juneau is an adventure involving a kayak ride or long hike and an ice climb. Entering the glacier itself is a magical experience, with no two visits ever quite the same due to its ever-changing structure. One thing that every visitor is blown away by is the stunning blue color of the ancient ice as the sun gleams through.
8. Waitomo Glowworm Caves, New Zealand
As the name suggests, it’s the resident insects of this cave on New Zealand’s north island that make it unique. Take a boat ride or step up the adventure with some blackwater rafting, caving or abseiling, under the illumination of the unique glow worm species that are only found in New Zealand.