Phong Nha Cave Tours: Son Doong, Paradise Cave, and How to Book

Phong Nha-Ke Bang National Park in Quang Binh province contains the world’s largest cave by volume and arguably the most dramatic underground landscapes anywhere on earth. The park covers 885 square kilometres of limestone karst and has been a UNESCO World Heritage Site since 2003 — expanded in 2015 to acknowledge the scale of discoveries still being made. New caves are being mapped every few years. The ones already open to visitors range from accessible single-day trips to multi-day expeditions requiring months of advance planning.

The nearest town is Phong Nha, a small riverside settlement 50km north of Dong Hoi and 450km south of Hanoi. The town is the base for virtually all cave tours.

Son Doong: The World’s Largest Cave

Son Doong was measured by British cavers in 2009 and confirmed as the largest cave passage on earth by volume — large enough to contain a 40-storey building and with its own localised weather system, jungle ecosystems, and underground river. The main passage runs 9km and reaches 200m in height.

Access is strictly controlled. Oxalis Adventure holds the exclusive licence to run Son Doong tours, by arrangement with the national park authority. The licence limits the number of visitors to 1,000 per year — roughly 220 groups of 4–6 people over the February–August season.

What the Tour Involves

The Son Doong expedition runs over 4 nights and 5 days, covering approximately 50km of hiking through jungle, river crossings, and the cave itself. Groups camp inside the cave. Porters carry camping and cooking equipment; the kitchen team produces full meals inside the cave. Physical fitness is required — the approach trail involves steep climbs and river wading before you even enter the cave.

Inside, the highlights include:

• The Garden of Edam: A doline (collapsed ceiling section) where daylight penetrates and an underground jungle grows on the cave floor
• The Great Wall of Vietnam: An 80m calcite barrier inside the cave, requiring ropes and fixed equipment to climb
• Hand of Dog: A stalagmite formation reaching 70m tall — among the largest ever recorded
• The underground river, navigable by swimming or inflatable raft

Booking and Cost

Cost: Approximately $3,000–$4,000 per person (prices adjusted annually by Oxalis as of 2026). Includes all meals, camping equipment, porter fees, national park fees, and guides. International flights and accommodation in Dong Hoi/Phong Nha before and after are separate.

How to book: Through Oxalis directly at oxalisadventure.com. Tours for the upcoming season typically open in late September/October. The 2026 season was fully booked within weeks of opening. Book 12–18 months ahead for any realistic chance of a spot. Oxalis maintains a waitlist.

Age and fitness requirements: Minimum age 16. No maximum age, but the expedition involves 6–8 hours of walking daily, cave swimming, and technical rope sections. Oxalis conducts a pre-departure fitness assessment.

Hang En: The World’s Third Largest Cave

Hang En is accessible on a 2-night/3-day expedition, also exclusively run by Oxalis. It is a more achievable version of the Son Doong experience — same jungle approach, same style of cave camping, but less technically demanding. The cave’s main chamber contains a river beach where groups camp, and a doline opening lets light flood in. Beach volleyball has been played in the cave; the scale is that large.

Cost: Approximately $600–$800 per person for the 3-day expedition (as of 2026), including all meals, equipment, and guides.

Advance booking required: Tours sell out 3–6 months ahead. The window is shorter than Son Doong but still requires planning.

Paradise Cave

Paradise Cave (Thien Duong) is the most popular cave in the park that can be visited independently or on a standard guided tour. Discovered in 2005 and opened to tourists in 2010, it extends 31km underground — the first 1km is lit and boardwalked for standard visitors; a 7km extension is available on a longer guided tour.

The main accessible chamber is where the phrase “cathedral-scale” is genuinely justified. Stalactites and stalagmites reach 30–40m, formations that took millions of years to develop. The boardwalk route keeps visitors off the cave floor, and the lighting (though artificial) is restrained enough that it doesn’t overwhelm the natural atmosphere.

Entry fee: Approximately 250,000 VND ($10 as of 2026) for the standard 1km boardwalk access. An electric buggy (additional approximately 70,000 VND) covers the first 2km to the cave entrance if you don’t want to walk. Extended 7km tour: Approximately 980,000 VND ($39) per person including guide; this requires advance booking and involves ropes and more demanding terrain.

How to get there: Paradise Cave is 19km from Phong Nha town. Most guesthouses arrange motorbike taxis for approximately 100,000–150,000 VND return. Many visitors combine it with a Phong Nha Boat Cave visit on the same day.

Phong Nha Boat Cave

Phong Nha Cave — the cave the town is named after — is reached by wooden motorboat along the Son River. The 1.5km river journey into the cave is the experience: you sit in the boat while guides navigate through the illuminated cavern, past riverside Buddhist shrines and past formations that Vietnamese kings once came to pray at. The cave was used as a weapons depot and field hospital during the American War.

Entry fee: Approximately 150,000 VND ($6 as of 2026) for the cave ticket. Boats hold 12–14 people and depart from the pier in Phong Nha village. The trip takes 1–1.5 hours. Boat hire is by the boat rather than per person — you may be combined with other visitors to fill the boat.

Notes: Photography is permitted but tripods require a permit. The cave interior is humid and warm; light layers are fine.

Dark Cave

Dark Cave (Hang Toi) is the park’s designated adventure tourism experience. The approach is a zip-line from the riverbank into the cave entrance over the Son River. Inside, the route involves swimming, kayaking through underground passages, navigating through total darkness with headlamps, and emerging into a large mud pool chamber where visitors — by design and by tradition — immerse themselves in mud.

This is messy, physical, and deliberately not for everyone. Guides are experienced, safety equipment is provided, and the operation is well-run by the Phong Nha Farmstay, which manages Dark Cave access.

Cost: Approximately 450,000 VND ($18 as of 2026) per person for the Dark Cave adventure including equipment (wetsuit, kayak, headlamp, zip-line). Bookable at Phong Nha Farmstay (the main operator) or through most accommodation in Phong Nha town.

Physical requirements: Comfortable in water, no serious claustrophobia. The tightest passage requires crawling on your stomach for a short section. Ages 6+ permitted, but younger children should be assessed by parents for comfort with the confined dark sections.

Tu Lan Cave System

Tu Lan is a multi-cave system about 65km north of Phong Nha town. The 2-night/3-day expedition involves jungle trekking, multiple cave entries, underground river swimming, and camping on cave beaches. It is less famous than Son Doong but shares the same kind of raw, exploratory atmosphere — routes involve genuine swimming and wading rather than boardwalk touring.

Operators: Oxalis runs Tu Lan expeditions alongside several smaller local operators (Green Jungle Tour, Tu Lan Cave Tour). Costs vary — Oxalis charges approximately $250–$350 per person for 2 nights; local operators from approximately $150–$200.

Season: Best February to August. Some routes close during heavy rain periods.

Practical Logistics for Phong Nha

Getting There

From Dong Hoi: The nearest train and air hub, 50km south of Phong Nha. Regular trains from Hanoi (6–7 hours, from approximately 170,000 VND / $7 for a hard sleeper) and from Da Nang (3 hours). Local buses and taxis connect Dong Hoi to Phong Nha town (approximately 150,000–200,000 VND by taxi; 50,000 VND by shared minibus, journey 1 hour).

From Hue or Da Nang: Possible as a long day trip but logistically tight. Most visitors extend to at least one overnight. The drive from Hue to Phong Nha takes approximately 3–3.5 hours via the Ho Chi Minh Road — a scenic route through the mountains.

Where to Stay

Phong Nha town has grown significantly in recent years. Accommodation ranges from backpacker hostels (from approximately 120,000 VND / $5 per night) to well-designed guesthouses and boutique hotels.

Phong Nha Farmstay (the original and still the most popular mid-range option) is 5km from town on the river, with a pool, good restaurant, and direct access to Dark Cave booking. Rooms from approximately $35/night.

Chay Lap Farmstay sits inside the national park near the Paradise Cave access road — quieter than town, better for early morning starts. Rooms from approximately $40/night.

Budget options in town: Easy Tiger Hostel and Phong Nha Friends Hostel are well-regarded, sociable places from approximately $8–$15/night.

What to Budget

A 2-day Phong Nha visit covering Paradise Cave + Phong Nha Boat Cave + Dark Cave costs approximately:

• Cave entry (Paradise + Phong Nha): approximately $16
• Dark Cave adventure: approximately $18
• Accommodation: $10–$35/night
• Food and transport: approximately $15–$25/day

A 3-day visit adding a Tu Lan expedition (local operator): add approximately $150–$200. A 5-day visit including Son Doong: add approximately $3,000–$4,000.