United States · Mammoth Cave (Mammoth Cave)
Mammoth Cave is the longest cave in the world, located within Mammoth Cave National Park in central Kentucky, USA, and is one of the UNESCO World Natural Heritage sites. Named after the ancient, long-haired mammoths, this “behemoth” cave had been explored to a length of nearly 600 kilometers as of 2006.

With mysterious pools, underground waterfalls, and delicate gypsum cave formations… once you’ve walked through, these stunning sights are sure to be etched into your memory forever. All caves here require advance registration, have varying opening schedules, and some even require safety gear to enter—making it a high-difficulty, thrilling cave exploration experience.

Italy · Blue Grotto (The Blue Grotto)
The Blue Grotto is located on the island of Capri, Italy, famous for its shimmering, almost fairy-tale-like sapphire-blue waters, and is hailed as one of the Seven Wonders of the World. The cave’s entrance lies beneath a cliff and is so small that access is only possible by boat.

The Blue Grotto is a sea cave measuring 60 meters long and 25 meters wide. Due to the unique structure of the cave’s entrance, sunlight enters through the mouth and reflects up from the water’s floor, casting the water and surrounding rocks in a brilliant blue—hence the name “Blue Grotto.” The blue reflections and refracted sunlight transport you to another magical realm.

Russia · Volcanic Ice Cave (Ice Cave Near The Mutnovsky Volcano)
This bizarre volcanic ice cave is located on the Kamchatka Peninsula in Russia. A stream of hot water flows beneath the glaciers on both sides of Mutnovsky Volcano, forming a nearly one-kilometer-long tunnel, which gives rise to the volcanic ice cave.

In recent years, the glaciers on the Kamchatka volcanoes have begun to melt, making the cave’s ceiling now very thin, allowing sunlight to pass through and illuminate the ice structures inside—creating an extraordinarily beautiful and surreal scene.

Mexico · Naica Mine (Naica Mine)
The Naica Mine is located deep underground in the Chihuahua Desert of Mexico, extending 1,000 feet down, and is renowned for its unique crystals. The Naica Crystal Cave is the largest crystal cave in the world.

The interior terrain of the Naica Mine is extremely complex, with crystals scattered throughout the cave in peculiar shapes, making navigation very difficult and turning the site into a paradise for explorers.

Iceland · Vatnajökull Glacier Cave (Vatnajokull Glacier Cave)
Vatnajökull Glacier is located in southeastern Iceland and is the largest glacier in Europe, second only to those in Antarctica and Greenland. At about 1,500 meters above sea level, the glacier’s dynamic nature makes it an iconic sight in Iceland.

Currently, Vatnajökull Glacier is flowing into warmer valleys at a rate of 800 meters per year. More intriguingly, the glacier area also features lava fields, volcanic craters, and hot lakes, earning it the nickname “land of fire and ice.”

Vietnam · Son Doong Cave (Son Doong Cave)
Son Doong Cave is located within Phong Nha-Ke Bang National Park in Vietnam, with most sections having a cross-section of approximately 80×80 meters. Discovered by expedition members in the remote jungles of Vietnam, they believe Son Doong Cave surpasses Malaysia’s Deer Cave in Borneo to become the largest single natural cave in the world to date.

Explorer Spillane said: “The airflow in this enclosed space creates a massive sound—you can hear the river flowing from the cave entrance. The noise is so loud, it evokes a sense of awe.”

Malaysia · Batu Caves (Batu Caves)
Batu Caves is a Hindu pilgrimage site featuring multiple Hindu shrines, hence it is also known as Temple Cave. Located 11 kilometers north of Kuala Lumpur, it is a cluster of limestone caves nestled on a jungle-covered mountainside. Visitors can reach it by climbing 272 steep steps from the base or take a cable car directly to the cave entrance.

Discovered over 100 years ago, the cave is most famous for its Dark Cave and Light Cave. The Light Cave stands about 50–60 meters high and 70–80 meters wide, named for the sunlight streaming in through holes in the cave ceiling. The Dark Cave is located to the left of the Light Cave, stretching 366 meters in length, dim, cool, with steep and winding paths—and home to thousands of bats and snakes.

United States · Mendenhall Glacier Cave (Mendenhall Glacier Cave)
The Mendenhall Glacier Cave is situated in the Mendenhall Valley near Juneau and is a karst glacier formed by summer glacial melt, resembling a rocky cave. Glacier caves like this can form within months or a few years, but they have a short lifespan and may collapse at any time.

Therefore, explorers must wear safety ropes and use ice axes to venture several hundred feet into the ice cave to admire its spectacular, otherworldly ice formations. Inside, you’ll find bizarre ice sculptures with no signs of life—giving the eerie feeling of stepping onto another planet.

New Zealand · Glowworm Caves (Glowworms Cave)
The Waitomo Glowworm Caves (also called Glowworm Caves or Waitomo Caves) are located in the Waitomo Caves region of Waikato, New Zealand, and are famous for their subterranean cave phenomena. Beneath the surface, limestone layers form a vast cave system adorned with various stalactites, stalagmites, and glowworms.

It resembles a mystical, starry night sky in the dark. Walking through a 250-meter underground passage and taking a boat into the depths of the cave, once your eyes adjust to the darkness, you’ll witness thousands of glowworms lighting up the cavern with tiny points of light—a truly fairytale-like scene of romance and beauty.

Thailand · Phraya Nakhon Cave (Phraya Nakhon Cave)
Phaya Nakhon Cave is located within Khao Sam Roi Yot National Park, near Ban Pu Village. The cave sits on a small island that was originally a reef formed when sea levels dropped. At the top of the cave is a natural skylight, creating a natural light source. When sunlight streams in from the cave’s ceiling, the golden, resplendent interior is truly breathtaking.

There is also a four-cornered palace built during the reign of King Rama V of Thailand, which has now become a symbolic landmark of Prachuap Khiri Khan Province. This spot sees few visitors, with crystal-clear waters that showcase the beauty of a southern island—simple, tranquil, and perfect for some quiet contemplation or daydreaming.

USA · Antelope Canyon
Antelope Canyon is one of the world’s most famous slot canyons, located in northern Arizona, USA, and is also a renowned photography destination. As one of the most beautiful canyons in North America, it is deep yet not very long, but cuts deeply into the earth along the mountain terrain. Antelope Canyon is geographically divided into two separate sections, known as Upper Antelope Canyon and Lower Antelope Canyon.

The geological formation here consists of the famous red sandstone, and the rocks inside the canyon have been eroded by flash floods into a dreamlike landscape. According to Navajo oral history, this area was once a habitat for pronghorn antelopes, and the canyon often saw these animals roaming about—hence the name Antelope Canyon. The older generations of the Navajo people once regarded this place as a sacred site for meditation and communication with the Great Spirit.