The World’s Top 5 Underground Rivers and Caves You Can't Miss

What is an Underground River (Subterranean River)?

An underground river or subterranean river is a natural wonder where water flows beneath the Earth's surface. Unlike the rivers we see on land, underground rivers hide in the darkness of caves, cracks in the ground, or even under the ocean. Their existence creates a unique and mysterious world that sparks our curiosity.

There are many reasons why underground rivers form. Sometimes, rain or water from surface rivers seeps into the ground, creating underground streams. In areas with special rock formations like limestone, water can dissolve the rock and create huge caves, holding a complex system of underground rivers. Additionally, underground rivers can also be formed by the movement of tectonic plates.

Exploring and studying underground rivers not only helps us understand the diversity of nature but also brings many benefits. Underground rivers can be an essential source of fresh water for areas with water scarcity. They also play a crucial role in maintaining the ecological balance of underground and surface ecosystems.

Kayaking in Hang Ba’s underground river. Nguồn: Oxalis Adventure

Exploring underground rivers is exciting, but safety comes first! Not all of these hidden waterways are safe for exploration. Some are too dangerous due to unpredictable currents or unstable rock formations.

Always prioritize safety and join guided tours led by experts with the proper knowledge and equipment. Not only will you have a safe and informative adventure, but you'll also get to share the experience with fellow explorers and make new friends!

#1 Son Doong's Underground river, Vietnam: A Top Must-visit Cave

Hang Son Doong, located in the heart of Vietnam's Phong Nha-Ke Bang National Park, is not just the world's largest cave, it's also home to a mesmerizing underground river. This subterranean river results from the confluence of the Rao Thuong River flowing from Hang En Cave and the waters from the Khe Ry Cave, the longest river cave in Vietnam.

Accessing this underground river in Son Doong Cave is an adventure in itself. Visitors must navigate through knee-deep waters from the cave entrance, crossing the river twice to reach the breathtaking “Hope and Vision” passage.

The trek is accompanied by the enchanting sounds of rumbling waterfalls and the ethereal sight of mist rising from the river, creating an otherworldly ambience. After winding its way through the cavernous expanse of Son Doong Cave, the river mysteriously vanishes near Doline 1, approximately 4.5 kilometres from the cave entrance. This intriguing disappearance adds to the allure and mystique of this underground realm.

You'll encounter otherworldly formations within the cave, towering stalagmites up to 80 meters high, massive cave pearls, and ancient fossils. The sunlight filtering through the two massive dolines illuminates the underground jungle, creating a surreal and breathtaking landscape.

How to get there: The only way to explore the cave is through a 6-day, 5-night guided expedition with Oxalis Adventure, the sole company authorized to operate tours. Due to the cave's fragility and conservation reasons, only 1000 guests are permitted to join Son Doong Cave Expedition tour every year.

The underground river beneath the Great Wall of Vietnam stretches over 600m.

#2 Rio Secreto, Mexico

Near Playa del Carmen, Rio Secreto (Secret River) is a mesmerizing underground river adorned with stunning crystal formations and crystal-clear water. This natural wonder is discovered relatively recently and is a testament to the hidden treasures beneath the Earth's surface.

Visitors can explore the cave's intricate network of waterways on guided tours, marvelling at the delicate beauty of its geological formations. Conservation efforts are in place to preserve this fragile environment and ensure its long-term preservation. In addition, for a more intimate and customised experience, each group is restricted to no more than ten people.

How to get there: The Waitomo Caves are located on the North Island of New Zealand, about a 2.5-hour drive from Auckland or a 1-hour drive from Hamilton. Organized tours and shuttle services are also available from major cities.

Rio Secreto is a stunning underground river with crystal formations and clear water, a recent natural marvel. Nguồn: Wikipedia

#3 The Waitomo Glowworm Caves, New Zealand

Prepare to be mesmerized by the Waitomo Glowworm Caves, a subterranean river where thousands of tiny glowworms illuminate the darkness like a starry night sky. The easiest way to witness this magical spectacle is through a guided walking or boat tour, gliding silently along the underground river while marvelling at the twinkling lights above.

If you crave more adventure, the Black Water Rafting experience is calling your name. You'll crawl, swim, and float through the cave system on a rubber tube, encountering hidden waterfalls and thrilling rapids. Try abseiling or zip-lining through the cavernous darkness for the ultimate adrenaline rush.

How to get there: The Waitomo Glowworm Caves are about 2.5 hours south of Auckland. The easiest way to get there is by car or organized tour.

Experience the enchanting Waitomo Glowworm Caves, where glowworms light up like stars in a subterranean river. Nguồn: headout.com

#4 Puerto Princesa Underground River, Philippines

A UNESCO World Heritage Site, the Puerto Princesa Underground River boasts a unique ecosystem teeming with biodiversity. Stretching almost five miles, it's one of the world's longest underground waterways, carving impressive cave formations as it flows into the sea. To protect this fragile environment, only 600 visitors are allowed per day.

A guided boat tour takes 45 minutes through one mile of this breathtaking underground world. Marvel at the intricate stalactites and stalagmites and look for diverse wildlife, including crab-eating monkeys, Tabon birds, and white-bellied sea eagles.

How to get there: The Puerto Princesa Underground River is about 50 km north of Puerto Princesa City, Palawan. You can take a bus or van from the city to Sabang, the jump-off point for the underground river tour.

Puerto Princesa Underground River features a diverse ecosystem rich in biodiversity. Nguồn: Viator

#5 Tu Lan Cave System's Underground River, Vietnam

The Tu Lan Cave System in Vietnam is a hidden gem that offers an unforgettable adventure for both thrill-seekers and families. Nestled in the Tan Hoa commune, about 70 km northwest of Phong Nha-Ke Bang National Park, the Rao Nan River forms this remarkable cave system. The system features several interconnected caves, such as Hung Ton Cave, Kim Cave, Tu Lan Cave, and Ken Cave, each with its underground river.

As you trek through the lush jungle, the anticipation builds for the subterranean rivers that await. Descending into the caves, you'll be greeted by a labyrinth of passages, stalactites, and stalagmites, all sculpted by the relentless flow of water over millennia.

The most exhilarating part of the journey is swimming in the underground river that winds through the cave system. Gliding through the cool, crystal-clear water, surrounded by towering cave formations, is truly surreal. The darkness envelops you, heightening your senses and creating a feeling of awe and wonder.

Many of the river caves culminate in a stunning waterfall that cascades into a jade-green lake surrounded by a sandy beach. These idyllic spots serve as campsites for multi-day expeditions, offering a chance to sleep under the stars and fully immerse yourself in the wilderness.

How to get there: The Tu Lan Cave System is accessible via guided tours offered by Oxalis Adventure Tours. The tours, which last from 1 to 6 days, typically involve trekking through jungle terrain, camping in the forest, and swimming through underground rivers.

Puerto Princesa Underground River features a diverse ecosystem rich in biodiversity. Nguồn: Viator

The allure of subterranean rivers and underground waterways is undeniable. These hidden gems offer a glimpse into the Earth's raw beauty and a chance to explore nature's artistry in its purest form. Whether you're an avid adventurer or a curious traveller, these top 5 underground river experiences promise to leave you in awe of the wonders that lie beneath your feet.

The Oxalis Experience.