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Hung Thoong Exploration: four caves: nightmare sharp, tron, hung and thung

Phong Nha, Vietnam

Hung Thoong Exploration

Length
3D2N
How hard is it
Hard
Group size
30
Minimum age
16+

Only here: The only trip with a kilometre-long swim through a flooded cave, and a zipline over a sinkhole.

Four caves in three days across a system opened in 2023, including a swim through Tron cave and a zipline over a sinkhole.

What you actually do

  • Four caves: Nightmare Sharp, Tron, Hung and Thung
  • A one kilometre swim through Tron cave in blue underground water
  • A 60 metre zipline across the Nightmare sinkhole
  • A 25 metre rope descent into Thung cave
  • The Floating Lake and the Ma Da crystal lake
  • A system only opened to visitors in January 2023

Is this the right tour for you?

Worth reading before you book. Age limits and group rules rule people out more often than fitness does.

Book it if

  • You want variety: swimming, ziplining, abseiling and caving in one trip
  • You are a confident swimmer. A kilometre in a flooded cave is a lot of water
  • You want a system that few people have been through
  • You are 16 or older and reasonably fit

Look elsewhere if

  • You are a nervous swimmer. This is the wettest tour in the catalogue
  • You want to be back in a bed each night. Two nights are camped
  • You are under 16

Day by day, all 3 of them

  1. Into the system

    Briefing and kit in Phong Nha, then into the forest towards the Hung Thoong group. The first day works through the outer caves of the system and reaches the sinkhole area, where the 60 metre zipline crosses the Nightmare collapse. Camp is set in the valley.

  2. Tron cave and the deep sections

    The centrepiece is Tron cave, roughly a kilometre of swimming through still, very blue water where the passage is flooded wall to wall. Later the rope team rigs a 25 metre descent into Thung cave. Between the caves the route passes the Floating Lake, which sits in a bowl of forest and rises and falls with the water table.

  3. Ma Da lake and out

    The last morning works back out through the system towards Ma Da and its crystal lake, with time to swim before the walk out to the road and the drive back to Phong Nha.

What the price covers

  • Guide, trained safety assistants and porters
  • All rope work, zipline, harness, helmet with headlamp and life jacket
  • Camping equipment and all meals
  • PVI travel insurance
  • Transfers within Phong Nha town

Not included: tips, personal spending, transfers from outside phong nha.

When to go

Runs year round. April and May are driest and clearest.

Questions worth asking first

How much of this tour is swimming?

A lot. The Tron cave section alone is around a kilometre of continuous swimming in a flooded passage, with more water elsewhere in the system. Life jackets are provided and safety staff swim with the group, but if you are uneasy in deep water this is the wrong tour and Hang Pygmy or Victory Cave would suit you better.

What is the Floating Lake?

A lake in a forest basin whose level moves with the water table, rising sharply in the wet months and dropping back in the dry. You pass it between caves.

Why did this only open in 2023?

New routes here need a survey and an operating licence from the national park before anyone can be taken through, which takes years. Hung Thoong received its licence and opened to visitors in early 2023, which by Phong Nha standards makes it recent, though Victory Cave in 2026 is newer still.

Is 12,000,000 VND good value against the Tiger Cave Series?

They cost within 500,000 VND of each other and both run three days. Hung Thoong is the wetter, more varied one, with a long cave swim, a zipline and a descent. The Tiger Cave Series is the drier one and camps at the Kong Collapse sinkhole. Pick on whether you would rather spend the trip swimming or walking.

How the price compares

Every tour here, cheapest first. Bars use a compressed scale so the shorter trips stay readable next to the expeditions.

Approximate figures, per person; the operator bills in VND. Cheapest is 800,000 VND (about $30), dearest is 79,500,000 VND (about $3,060).

If this is more than you wanted

Do Quyen Waterfall Top Adventure, Hue

Jungle Boss

Do Quyen Waterfall Top Adventure

2D1N

Descend 200 metres down the face of one of Southeast Asia's tallest waterfalls on rope, after a night camped at the Five Lakes and a training session on a smaller fall.

The only tour that abseils 200 metres down the face of the waterfall itself.

Hard
11,250,000 VND
about $435 · age 12+
Tiger Cave Series Adventure, Phong Nha

Jungle Boss

Tiger Cave Series Adventure

3D2N

Three connected caves and nearly seven kilometres underground, camping at the edge of the Kong Collapse sinkhole without doing the full expedition.

The only way to camp at the edge of Kong Collapse without committing to the five day expedition.

Hard
12,500,000 VND
about $480 · age 15+
Hang Tien Exploration, Phong Nha

Oxalis Adventure

Hang Tien Exploration

4D3N

Four days in the Tu Lan system near Tan Hoa: four caves, ladder descents on harnesses, cave swims, and two nights camped beside jade green lakes.

The largest dry cave of the Tu Lan system, in a different valley 70 km from Phong Nha that no other tour here touches.

Hard
10,900,000 VND
about $420 · age 16+

Photographs by Jungle Boss.

Plan the rest

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