Vietnam Cave

Hang Én (swift cave)

24 °C inside, all year.

The descent

The entrance, at 188 m.

The real relief above Hang Én (swift cave), measured on the Copernicus model every 30 m, and the cave going down at the same vertical scale.

The depth is the one published by those who explored it; the shape of the galleries is a sketch, not a survey. No depth has been published for this cave yet.

188m

Entrance altitude

from the 30 m relief model

24°C

Inside, all year

the yearly average outside, at the entrance

505m

Rock above

the highest point within 1.5 km

Inside and outside

24 °C inside, all year.

Deep inside, a cave keeps the average temperature of the year outside: about 24 °C here, in January and in August. In May the afternoon reaches 32 °C at the entrance, 8 °C warmer than inside: take a jacket. The best months to escape the heat are from March to October. The wettest months are from July to October: water rises fast underground, so never go in without a guide after heavy rain.

outside, at the entrance (188 m)inside

23°15°Jan
26°16°Feb
29°18°Mar
32°21°Apr
32°23°May
31°24°Jun
31°24°Jul
30°24°Aug
30°23°Sep
28°22°Oct
26°20°Nov
23°16°Dec

Inside: 24 °C all yearEscape the heat: Mar–OctWettest: Jul–Oct

Outside: afternoon and night averages for 1991–2020 (NASA POWER) brought to the altitude of the entrance. Inside: the yearly average, which deep parts of a cave keep. Near the entrance it follows the weather a little.

En Cave in Quang Binh Province, Vietnam

Hang Én (swift cave) is a cave in Vietnam. The entrance is at 188 m. It has an underground river.

Getting there.

Wild cave: only with caving equipmentNo paths or lights inside. Go only with a caving club or a qualified guide.
Xuân Sơnnearest town · 20 km in a straight line
Dong Hoi Airport (VDH)nearest airport with scheduled flights · 32 km in a straight lineCar hire in Nakhon PhanomDiscover Cars · sponsored link

Plan the visit

Guided tours, a bed nearby, a car.

Car hire in Nakhon PhanomDiscover CarsSee prices

Some links above are affiliate links: if you book through them we may earn a commission, at no extra cost to you. It never changes what the data on this page says.

The water

The the river runs highest from September to October.

The the river carries about 4.5 m³/s on average here. It runs highest from September to October. It is lowest from January to June.

1.6 m³/sJan
0.5 m³/sFeb
0.4 m³/sMar
0.8 m³/sApr
2.4 m³/sMay
2.9 m³/sJun
5.3 m³/sJul
7.9 m³/sAug
13 m³/sSep
17 m³/sOct
10 m³/sNov
4.8 m³/sDec

From about 0.41 m³/s in the lowest month to 17 m³/s in the highest. Its basin above this point covers 106 km².

Estimate: long-term flow from the HydroATLAS model (WaterGAP, 1971–2000) shaped by the monthly rain, snow and temperature of the area (NASA POWER). Dams change it. Not a forecast.

From above.

The ground above the cave, with the relief shaded, the line of the section and what people have mapped around the entrance.

The ground above Hang Én (swift cave) (Sentinel-2)

N 1.5 km

Cave entrancesCampsites

Sentinel-2 cloudless 2016 (EOX, CC BY 4.0), 6.0 × 6.0 km, north up. The line is the section above. Points © OpenStreetMap contributors.

Around the entrance.

4other cave entrances within 3 kmHang Sơn Đoòng, Hang Sơn Đoòng - Hồ Khanh, Hang Én and 1 more
2campsites within 8 kmBức tường Việt Nam, Oxalis Hang Va Camp

springs within 2 km
sinkholes within 3 km
caving clubs and spots within 15 km
viewpoints within 3 km
marked hiking routes within 3 km
climbing crags within 3 km
named waterfalls within 4 km
car parks within 2 km
information boards and visitor centres within 3 km
bus stops within 2 km
hotels and guesthouses within 8 km
restaurants and cafés within 3 km

Counted in OpenStreetMap, the map anyone can edit, around the entrance. A low number may just mean nobody has mapped it yet. © OpenStreetMap contributors (ODbL).

Towns nearby

Xuân Sơn20 km in a straight line

In our other atlases

What else is around Hang Én (swift cave).

The river at the entrance, the waterfalls, the lakes, the mountains and volcanoes above, the canyons, beaches and islands nearby — from our other atlases.

Peakyas6 mountains within 10 km

Co Tan · 6.8 kmPhu Giu Ha · 8.1 kmBa Gen · 8.7 kmNúi Co Choc · 9.1 kmCo Preu · 9.4 kmCo Khu · 9.9 km

Figures from the sister sites' databases (Wikidata, HydroATLAS, GeoNames, NOAA, OpenStreetMap). Links open when each site is online.

Month by month

The weather outside, at the entrance.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Afternoon	23	26	29	32	32	31	31	30	30	28	26	23
Afternoon	23	26	29	32	32	31	31	30	30	28	26	23
Night	15	16	18	21	23	24	24	24	23	22	20	16
Rain (mm)	36	23	41	60	122	111	192	233	345	379	140	79
Rainy days	8	6	8	10	18	19	21	24	23	21	16	12
Sun hours/day	1.8	3.0	3.2	4.8	6.4	6.4	5.8	5.1	4.4	3.0	2.3	1.0

	Afternoon	Afternoon	Night	Rain (mm)	Sun hours/day
Jan	23	23	15	36	1.8
Feb	26	26	16	23	3.0
Mar	29	29	18	41	3.2
Apr	32	32	21	60	4.8
May	32	32	23	122	6.4
Jun	31	31	24	111	6.4
Jul	31	31	24	192	5.8
Aug	30	30	24	233	5.1
Sep	30	30	23	345	4.4
Oct	28	28	22	379	3.0
Nov	26	26	20	140	2.3
Dec	23	23	16	79	1.0

Averages 1991–2020 (NASA POWER) for a cell about 55 km wide, brought to the altitude of the entrance (188 m) with the standard lapse rate. Not a forecast.

Photographs

Inside and around.

Desert Camping (Unsplash) — Siam Choudhury siam · CC0

Recent years

Wet years, dry years.

Rain of each month as a share of the 1991–2020 average. A dry year means a lower river and hotter rock; a wet one, more water in the gorge.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
2020	225%	197%	177%	135%	83%	29%	35%	135%	60%	415%	225%	145%
2021	98%	181%	125%	271%	58%	248%	156%	37%	227%	241%	100%	128%
2022	109%	271%	243%	274%	172%	72%	126%	90%	161%	146%	198%	180%
2023	151%	140%	77%	94%	89%	84%	78%	66%	108%	196%	193%	342%
2024	231%	76%	136%	12%	165%	100%	77%	35%	193%	166%	231%	164%
2025	128%	290%	126%	144%	134%	378%	99%	257%	127%	173%	329%	128%

130% or more: wet month 70% or less: dry month

Caves nearby.

Hang Én (swift cave)

Vietnam

—Depth
—Galleries
188 mEntrance altitude
24 °CInside, all year

Son Doong Cave

Vietnam · 3 km

—Depth
—Galleries
390 mEntrance altitude
23 °CInside, all year

See the guide

Thien Duong Cave

Vietnam · 13 km

—Depth
—Galleries
253 mEntrance altitude
24 °CInside, all year

See the guide

Phong Nha Cave

Vietnam · 17 km

—Depth
—Galleries
3 mEntrance altitude
26 °CInside, all year

See the guide

Where these figures come from

Name, type, published depth and length, visitors	Wikidata (Q22278419) · CC0
The relief above, the entrance altitude, the section and the 3D model	Copernicus DEM GLO-30 · © DLR e.V., © Airbus Defence and Space GmbH, Copernicus/ESA
River flow and basin	HydroATLAS / RiverATLAS v1.0 (Linke et al. 2019) · CC BY 4.0
Climate	NASA POWER, 1991–2020
Entrances, springs, sinkholes, opening hours and what is around	© OpenStreetMap contributors · ODbL
Images	EOX Sentinel-2 cloudless 2016 · CC BY 4.0; Wikimedia Commons
Rivers, waterfalls, lakes, mountains, canyons, beaches and islands nearby	Coastya, Lakeyas, Peakyas, Cascadyas, Islandyas, Riveryas

Every figure is an average, an estimate or a count from a public dataset. Licences and methods: data sources.

The family

Do you prefer beaches, lakes, mountains, waterfalls, islands, rivers, canyons, caves, dark skies, viewpoints, birdwatching or forests?

Same idea, other landscapes: field atlases built on open data, month by month, in seven languages.

beaches

Find your beach: sea temperature, sun and swimming month by month.Visit

lakes

Every lake on Earth: water temperature, ice, depth and the shore.Visit

mountains

Every summit in 3D: summit weather, the 0 °C line, huts and trails.Visit

waterfalls

Every waterfall: height, flow month by month and when it roars.Visit

islands

Every island from the sea up: size, sea temperature, ferries and 3D.Visit

rivers

Every river from source to sea: the journey, the flow and the basin in numbers.Visit

canyons

Every canyon cut to scale: depth to the floor, rim and floor temperatures, trails and viewpoints.Visit

caves

Every cave with its real depth and length: the rock above, the temperature inside all year, and how to visit.You are here

dark skies Darkskyas

Where the night is still dark: the sky of every place, the Milky Way month by month, the Moon, eclipses and auroras.Coming soonVisit

viewpoints Viewyas

Every viewpoint with its real 360° panorama: the peaks you can name, how far you see and where the sun sets.Coming soonVisit

birdwatching Birdyas

Every bird sanctuary and wetland with the species recorded month by month: who is resident, who comes for the summer, who only passes through.Coming soonVisit

forests

Every forest with its land-cover rings, what grows and lives in it, and the best months to walk it.Coming soonVisit

	Afternoon	Afternoon	Night	Rain (mm)	Sun hours/day
Jan	23	23	15	36	1.8
Feb	26	26	16	23	3.0
Mar	29	29	18	41	3.2
Apr	32	32	21	60	4.8
May	32	32	23	122	6.4
Jun	31	31	24	111	6.4
Jul	31	31	24	192	5.8
Aug	30	30	24	233	5.1
Sep	30	30	23	345	4.4
Oct	28	28	22	379	3.0
Nov	26	26	20	140	2.3
Dec	23	23	16	79	1.0

	Afternoon	Afternoon	Night	Rain (mm)	Sun hours/day
Jan	23	23	15	36	1.8
Feb	26	26	16	23	3.0
Mar	29	29	18	41	3.2
Apr	32	32	21	60	4.8
May	32	32	23	122	6.4
Jun	31	31	24	111	6.4
Jul	31	31	24	192	5.8
Aug	30	30	24	233	5.1
Sep	30	30	23	345	4.4
Oct	28	28	22	379	3.0
Nov	26	26	20	140	2.3
Dec	23	23	16	79	1.0

	Afternoon	Afternoon	Night	Rain (mm)	Sun hours/day
Jan	23	23	15	36	1.8
Feb	26	26	16	23	3.0
Mar	29	29	18	41	3.2
Apr	32	32	21	60	4.8
May	32	32	23	122	6.4
Jun	31	31	24	111	6.4
Jul	31	31	24	192	5.8
Aug	30	30	24	233	5.1
Sep	30	30	23	345	4.4
Oct	28	28	22	379	3.0
Nov	26	26	20	140	2.3
Dec	23	23	16	79	1.0