Hang En or Swallow Cave serves as the gateway to Son Doong Cave, featuring a stunning campsite inside the cave, unique geological landscapes, and the famous setting for Peter Pan: The Neverland. On the world-renowned expedition to conquer Son Doong Cave, the most challenging cave adventure on the planet, travelers will spend a day resting, camping inside Hang En, and exploring the world of swiftlets deep in the jungle.
The stunning campsite inside Hang En, shaped by millions of years of geological formation, features massive cave entrances and giant domes, attracting over 2,300 adventure seekers each year.
This article provides a comprehensive overview of Hang En, covering its location, history, exploration journey, tour costs, and essential tips for travelers passionate about the cave wonders of Phong Nha, Vietnam.
Overview of Hang En Cave
Location, formation process, and geological structure
Hang En is located deep within the core zone of Phong Nha – Ke Bang National Park, in Quang Tri Province. It is about 11 kilometers from KM35 on the western branch of the Ho Chi Minh Highway.
It is one of the most magnificent caves in Vietnam, located within an ancient limestone mountain system that formed approximately 350 to 400 million years ago. Stretching nearly 1.6 kilometers in length, Hang En features enormous cave chambers, with the highest dome reaching up to 145 meters and a width of nearly 200 meters.
According to surveys, Hang En has a total volume of 6.7 million m³, ranking behind Son Doong Cave (38.5 million m³) and Deer Cave in Malaysia (9.5 million m³).
Estimated to be around 2 to 3 million years old, Hang En was formed by the erosive flow of the Rao Thuong River through a massive limestone mountain block.
More than just a gateway, Hang En channels the river into Son Doong and also serves as a key resting point along the journey to conquer the world’s largest cave.
The cave structure includes three main entrances: an entering entrance, a large entrance where sunbeams stream directly into the cave, most spectacular between December and March, and the rear entrance.
The rear entrance is the largest, measuring 120 meters in height and 110 meters in width. It acts like a natural gateway, leading visitors from the cave’s darkness out into a wild valley on the path toward Son Doong Cave.
The discovery and exploration history of Hang En
Arem people have known about the existence of Hang En for decades. They regarded the cave as a safe shelter and used to catch swiftlets inside the cave as a food source.
The large entrance and rear chambers of Hang En provide an ideal nesting ground for millions of swallows. The vertical cave walls, heavily weathered by wind and flowing water, are marked by numerous horizontal ridges and indentations along the rock face. These natural formations unintentionally created handholds for the Arem people in the past.
With small but strong and resilient bodies, Arem men would weave jungle vines into makeshift rope ladders and climb the smooth, slippery cave walls using only their bare hands and feet to collect swiftlets. These weathered marks and climbing traces remain visible in the cave today.
In 1994, the British-Vietnamese Caving Expedition conducted an exploration and survey of the cave, officially recognizing Hang En as one of the largest caves in the world.
Since 2012, Hang En has been open to tourism through a 2-day, 1-night tour operated exclusively by Oxalis Adventure.
International media and the cinematic value of Hang En
Since its official announcement, Hang En has become a hot topic, drawing the attention of major magazines and film crews around the world. In 2011, a Japanese television station, NHK, produced a scientific documentary about Hang En, which was broadcast in 60 countries.
In early 2015, ABC’s Good Morning America collaborated with Oxalis, the leading cave adventure tour operator in Vietnam, to broadcast a live program featuring the exploration of Son Doong and Hang En. Their goal was to showcase the stunning beauty of these caves hidden in Vietnam’s tropical jungle to American audiences and adventure travel enthusiasts around the world.
This marked a significant milestone, and the Oxalis team enthusiastically supported the film crew with logistics and transporting over 4 tons of equipment to accompany the entire expedition and filming process. More than 150 porters and cave experts were involved throughout the production. The program aired on May 13, 2015, attracting over 6 million live broadcast viewers, 27 million online views, and countless positive responses.
Major media outlets, such as BBC, National Geographic Magazine, The New York Times, and Lonely Planet, have also featured this remarkable cave, bringing it to a global audience. The breathtaking and majestic scenery of Hang En was even showcased in the 2015 Hollywood film Pan: The Neverland, further inspiring adventure seekers from around the world to visit.
A key stop on the journey to conquer Son Doong
Hang En was the very first cave adventure tour operated by Oxalis Adventure, the company with over 15 years of experience organizing cave expeditions in Vietnam.
In 2014, when Son Doong Cave was officially opened for tourism, Hang En was selected by Oxalis as a key stop on the 6-day, 5-night expedition to conquer Son Doong.
Since then, Hang En has quickly become one of the most renowned cave adventure tours in Vietnam, welcoming around 2,300 to 2,500 domestic and international visitors each year.
For travelers with little to no trekking experience, Hang En is an ideal choice to start building endurance and confidence. Hang En Cave Adventure, along with other short expeditions like Hang Va Expedition Tour and Tu Lan Cave system, offers the perfect introduction to jungle terrain and climate, preparing visitors for more demanding adventures such as the Son Doong Expedition Tour.
The natural beauty of Hang En
Hang En is not only famous for its massive size but is also hailed as a “masterpiece of nature” thanks to its breathtaking beauty and rich internal ecosystem.
Majestic Cave Entrances and Domes
1. The entering entrance
Hang En features three cave openings, each a remarkable natural structure with its distinct character. The entrance is only about 3 meters high and is located at the base of a limestone mountain. It curves deeply inward, creating the illusion of a massive rock mass, seemingly weighing hundreds of thousands of tons, suspended overhead.
The cave walls here are several meters thick and have been weathered over millions of years by water and wind, leaving behind countless deep grooves and natural markings carved into the rock.
2. The large entrance
One of the most striking features of Hang En is its large cave opening that allows sunlight to stream in. This grand entrance collapsed approximately 500,000 years ago.
Beneath it lies a steep rocky slope, formed by countless layers of boulders and stones piled atop one another, creating a winding path that leads down to the underground stream and campsite inside the cave. This dramatic landscape is the result of hundreds of thousands of years of geological activity.
Right beneath the towering entrance lies the campsite beside an underground lake, where visitors are treated to a spectacular display of sunlight streaming down from above. On clear days—especially from December to March—sunbeams pierce deep into the cave, creating a shimmering, picture-perfect scene like something out of a painting.
3. The rear entrance
The rear entrance of Hang En is a geological marvel, measuring over 120 meters in height and 110 meters in width. It serves as a breathtaking rest point where visitors are captivated by the surreal view of blue skies, drifting clouds, untouched jungle, and thousands of swallows soaring through the majestic cave opening.
4. The Cave Dome
The enormous dome of Hang En is one of the most striking geological features of this world-class cave. Stretching 1.6 kilometers in length, with a total volume of 6.7 million cubic meters, the cave reaches up to 145 meters in height and nearly 200 meters in width at its widest point.
Upon entering, many visitors are overwhelmed and awestruck by the sheer vastness and grandeur of this underground world carved deep into the limestone mountains.
The underground river and stalactite formations
Another remarkable feature of Hang En is its calm, crystal-clear underground stream that flows from the Hung Doong Valley through the heart of the massive cave. This stream, fed by the Rao Thuong River, has carved through the mountain over time, combining with underground currents to create turquoise pools and soft sandy beaches. It’s the perfect spot for visitors to relax and enjoy a refreshing swim.
The stalactite system inside Hang En is no less grand, massive, or unique than those found in Son Doong, Hang Va, or the Tu Lan cave system. The formations here mainly include flowstones, coral stalactites, rimstone dams, and more that were shaped over millions of years by nature’s slow, artistic hand.
A unique ecosystem inside Hang En
More than just a giant rock chamber, the location and geological structure of Hang Én have given rise to a unique ecosystem. Sunlight streams through the cave entrances, creating favorable conditions for the growth of various plant species such as algae, mosses, and ferns.
In front of Hang En’s entrance, various wildlife such as gibbons and langurs can be found living and foraging. The darker middle chamber of the cave is home to bats, scorpions, and many other types of insects.
Hang En is also home to millions of swallows that have nested here for hundreds of years, especially concentrated around the front and rear chambers of the cave. These iconic birds are the inspiration behind the cave’s name – “En,” meaning “swallow” in Vietnamese. Every morning, the swallows fly out in search of food, and by late afternoon, they return in flocks, filling the quiet jungle with their cheerful, chirping sounds.
A unique experience in Hang En cave adventure
1. Trekking through the pristine jungle
The journey to Hang En takes visitors across 25 kilometers of Phong Nha – Ke Bang National Park, with an elevation change of around 650 meters. Over 70% of the trail leads through pristine jungle, where a rich ecosystem thrives beneath the canopy of centuries-old towering trees.
The terrain along the tour changes constantly, with uneven jungle trails, steep climbs, rivers and streams, and rocky slopes inside the cave, offering both challenge and excitement. Along the way, visitors may encounter rare forest birds, vibrant butterflies, and traces of wildlife such as flying squirrels, langurs, and macaques.
2. A stop at Ban Doong – A hidden village deep in the jungle
After trekking about 3.4 kilometers from KM35, visitors will arrive at Ban Doong, a small, isolated village nestled within Phong Nha – Ke Bang National Park. This is home to the Bru – Van Kieu people, an ethnic minority community who have lived in harmony with the jungle for generations.
Originally, this area was just a small elevated mound beside the Rao Thuong Stream. In 1992, after a flash flood swept away their homes, a group of Bru-Van Kieu people, led by Mr. Nguyen Soai Trac, relocated here to reclaim the land and establish the village.
Before 2003, Ban Doong villagers were almost completely isolated from the outside world, as the only way to reach Phong Nha town was by walking—often taking several days on foot. Later, with the construction of National Highway 15 (the western branch of the Ho Chi Minh Road), transportation became more accessible. Today, visitors can travel by motorbike or car from Phong Nha town for about 40 kilometers, then hike an additional 3.4 kilometers from KM35 to reach Ban Doong.
Today, Oxalis collaborates with local households in Ban Doong to make the village a stopover on both the Hang En cave adventure and Son Doong Expedition tours. Visitors have the chance to interact with the locals, learn about their culture and traditions, and enjoy a lunch prepared right in the heart of the village.
3. Camping inside the cave
One of the most unique highlights of the Hang En tour is the opportunity to camp right inside the vast cave itself. Located about 700 meters from the cave entrance, the campsite is set in the widest chamber of the cave, next to an underground lake and the skylight opening where sunlight streams in. Oxalis provides guests with personal tents, sleeping bags, clean mattresses with fresh covers, dining tables and chairs, hot coffee and tea, as well as delicious hot meals prepared by a professional chef.
Sleeping inside a cave is a rare and unforgettable experience that few places in the world can offer. Deep in the remote wilderness, Hang ÉEn feels like a natural shelter that is intentionally crafted by nature itself.
Guests will sleep in cozy tents, gaze at the starry night sky through the massive cave opening, and listen to the quiet breath of the jungle that is still tinged with the chill of stone, mountains, and forest air. The towering ceiling of Hang En, rising over 145 meters high, is adorned with countless rock veins in varying colors, blending and swirling like drifting clouds above.
In the morning, visitors are greeted by brilliant rays of sunlight streaming down from the high entrance, illuminating the campsite and the crystal-clear underground lake. It’s a magical, almost surreal beauty that leaves a lasting impression on all who have set foot in this extraordinary place.
At Oxalis, there are three adventure tours where guests can experience camping and sleeping inside a cave: Hang En cave adventure, Hang Ba deep jungle expedition, and Son Doong expedition tour. Among them, the campsite inside Hang En is considered one of the most beautiful and unique cave campsites in the world.
4. A unique natural pool inside the cave
The underground stream in Hang En is formed by the warm flow of the Rao Thuong River combined with a cooler underground current. The water temperature stays between 17°C and 25°C, refreshingly cool in the summer and pleasantly warm in the winter.
After a full day of trekking over 10 kilometers through the jungle, visitors can unwind by swimming and relaxing in the cool, refreshing pool nestled inside the cave. The crystal-clear underground stream is home to countless tiny fish. As guests soak or dip their feet in the water, schools of these little fish will gather and gently nibble at their feet—an experience often referred to as a natural “fish massage.”
5. Geology and geomorphology inside Hang En
The middle chamber of Hang En reveals a magnificent world of geological wonders. Massive rock formations, shaped and displaced by tectonic forces, have fallen to the cave floor, stacking into steep rocky slopes. Some sections drop dramatically beside deep chasms. This area is also a favorite gathering spot for swifts. With a bit of luck, visitors might spot their nests and eggs perched on rock ledges along the trail.
Deep inside the dark cave lies a hidden world of bats, crickets, and most notably, stunning formations such as coral stalactites, flowstones, and rimstone dams resembling cascading waterfalls that block parts of the path.
Standing at the center of the main chamber, visitors can see faint light streaming in from both the front and rear entrances of Hang En. These two glowing openings create an iconic visual that is often compared to the eyes of Spiderman or the nostrils of Kong from Kong: Skull Island.
How to book Tour explore Hang En 2-day
Currently, the 2-day, 1-night Hang En cave adventure is operated exclusively by Oxalis Adventure. To join the tour, visitors are required to book in advance through the Oxalis Adventure website.
Visitors can travel to Dong Hoi by plane, train, or sleeper bus. From there, they can take an additional 45-kilometer journey to the Oxalis Adventure office in Phong Nha commune (Oxalis Home) by shuttle bus of Oxalis, taking a taxi, or riding a local bus.
For more details on transportation options, costs, and services, visitors can refer to the article “How to Get to Phong Nha” on the Oxalis Adventure website.
If arriving early on the morning of the tour departure, visitors can rest for free in the dormitory room at Oxalis Home. For those arriving one or more days in advance, accommodation is available at Oxalis Home with both dorm and private room options, or at the nearby Commander Lodge (just 500 meters away), offering cozy and comfortable stays.
Cost
The total cost of the Hang En cave adventure is 333 USD (8,800,000 VND per person). This price includes VAT, forest environment fees, entrance tickets, and travel insurance.
Tour regulations and requirements
The Hang En trekking tour is designed for guests aged 16 to 70, with a maximum of 16 participants per tour. To join, visitors must meet the following requirements:
- Have prior trekking experience: either one overnight trek or 2–3 full-day treks.
- Commit to providing accurate information about their health and trekking experience when registering.
- Be physically fit, able to run 5 kilometers in 50 minutes, or climb five flights of stairs continuously without experiencing shortness of breath or dizziness.
- Children under 16, adults over 70, and individuals with serious medical conditions are not eligible for the tour.
- Follow all instructions from the guide and safety assistants strictly at all times.
For those who do not yet meet the fitness requirements, Oxalis Adventure offers consultations and personalized training plans through its adventure consultants.
Best Time to Visit Hang En Cave
Hang En cave adventure tours operate from December to mid-September each year. From late September to November, the region enters the rainy season, so Oxalis Adventure temporarily suspends all trekking and cave exploration activities in Hang En to ensure visitor safety.
Each time of year offers a unique beauty and experience in Hang En:
- December to March: The weather is cool and occasionally sunny. During this period, sunbeam can reach deep into the cave, creating a magical atmosphere—perfect for photography.
- April to May: The primary forest enters the blooming season, with vibrant scenery and pleasant weather. This is an ideal time for nature lovers and photography enthusiasts.
- June to August – Summer season: While outdoor temperatures can be high during summer, most of the trekking route is shaded by forest canopy, keeping the journey relatively cool. Inside the cave, the temperature remains comfortable at around 22–25°C, and the underground stream offers refreshingly cool water.
Safety and environmental conservation guidelines
Visitors are expected to follow specific safety rules and conservation guidelines during the Hang En cave adventure, including:
- Wear proper trekking shoes and quick-dry clothing.
- Always wear a safety helmet and headlamp when entering the cave (provided by Oxalis).
- Life jackets must be worn when swimming in underground rivers or pools.
- Stay with the group at all times; do not separate from the team.
- Respect the natural environment and keep noise to a minimum inside the cave.
- Do not litter, pick flowers or plants, or disturb the forest and cave ecosystems.
- Never touch cave formations such as stalactites and stalagmites.
- Avoid using chemical-based shampoos, soaps, or body wash when bathing in the cave’s underground pools.
Amid countless captivating destinations, Hang En stands out as a pristine cave with a uniquely scenic campsite and as the gateway to the world’s largest cave. But perhaps, it’s only when you trek through the jungle, wade across streams, and listen to the echoing calls of swifts deep in the stillness of the forest, that you’ll truly feel the awe-inspiring beauty of this extraordinary place.
Get ready to embark on an unforgettable journey to conquer the majestic natural wonder known as Hang En!