The short answer
Ha Long Bay is a sea full of stone: an area of the Gulf of Tonkin off north-eastern Vietnam crowded with steep limestone islands, some 1,600 of them or about 2,000, depending on where the bay is said to end, and 989 have names. Hạ Long means “descending dragon”, and the name is young for so old a place: it turns up in the late nineteenth century, on a French maritime chart.
From Tally’s diary
Woke on a boat to a mist full of stone: steep towers with jungle on their heads, standing straight up out of flat green water, each one nibbled in at the waterline. A woman rowed me through a tunnel so low I ducked, into a round lake that seemed to have no other way in, and no wish for one. Houses floated past with dogs on the porches. I gave up counting towers and waved at them instead.
Why it's worth knowing
The postcard shows islands. The geology says hills. Most of the islands are single towers of a classic tower-karst landscape, mostly 50 to 100 metres high and about six times taller than they are wide, with clusters of cone-shaped hills among them. The limestone took some 20 million years to weather into towers on dry land. Then the sea came in, and the present bay took shape after it reached its highest, a few thousand years ago.
March 2008Towers in the mist astern of the boat, its wake running back towards them.
Photograph: Vyacheslav Argenberg, CC BY 4.0
That is why the bay is listed for its geology as well as its beauty. Nowhere else in the world has the sea flooded a landscape of limestone towers on this scale.
The field notes
The line at the waterline
The sea did more than fill the valleys. Seawater dissolves limestone where it touches it, and the waves work at the same level, so the foot of almost every tower is undercut in a horizontal groove at the tide line, where the water rises and falls 3.5 to 4 metres. The marine notch is a feature of limestone coasts everywhere; in Ha Long Bay it has shaped a whole landscape.
March 2013A limestone tower undercut at the tide line by the notch the sea has dissolved into it.
Photograph: Jean-Marc Astesana, Halong, CC BY-SA 2.0, cropped
In places the notches have been deepened into caves that pass right through a hill into a drowned sinkhole, now a tidal lake. Dau Be island, at the mouth of the bay, hides six enclosed lakes, among them the Ba Ham lakes; the way into the first is a notch cave that curves for about 150 metres, so that it is almost completely dark. A marine notch cave gives itself away by its ceiling: smooth, flat and cut level through the rock.
Older caves, higher up
The caves most visitors see were made differently, when the karst was still dry land. The largest, Hang Dau Go, survives between 20 and 50 metres above the sea on Dau Go island. French tourists in the late nineteenth century called it the Grotte des Merveilles, and its chambers still carry their nineteenth-century graffiti.
January 2024Inside a cave on one of the bay's islands.
Photograph: Jakub Hałun, CC BY 4.0
Living on the water
People have lived round the bay for a very long time, beginning with the Soi Nhụ culture of fish and shellfish gatherers more than ten thousand years ago. Until recently some 1,500 to 1,600 people lived in fishing villages on the bay itself, in floating houses, fishing and farming fish. Since May 2014 the Quang Ninh provincial government has moved more than 300 households ashore and kept a few villages for visitors. The villages that remain are still homes.
Boats at anchor among the limestone islands in late-day light.
Photograph: Vivu Vietnam via Unsplash, Unsplash licence
January 2020The bay from the summit of Ti Tốp island.
Photograph: Steffen Schmitz (Carschten), CC BY-SA 4.0
- Spend a night on the water if you can. The towers are different company at dawn.
- Remember the floating houses are homes. Wave, buy something if you want it, and ask before pointing a camera at anyone’s porch.
- When the crew says the weather is turning, believe them first and ask why afterwards.
- Look for the groove the sea has cut round the foot of every tower, then try to stop seeing it everywhere.
- Give one tower a name for the list. (Named several and could not find any of them again. There is now a page of names out there, looking for their towers.)
A relic from Ha Long Bay
Relic, entry 108Cut by: the tideFound: round almost every tower
The notch. Round the foot of almost every limestone tower in Ha Long Bay runs a horizontal groove, cut in at the level of the tide, where seawater has dissolved the rock and waves have worn it back.
Tally, in the marginA groove round the foot of every island, neat as the ring on a bath. Hills, then, that the sea came in and sat down among, and the ring is where it has been sitting.
Getting there
- 1
From Hanoi
By road, on the expressway to Ha Long.
- 2
Or by air
Van Don International Airport, about 50 kilometres away.
- 3
Into the bay
Day boats and overnight cruises from Ha Long’s harbours.
- ✓
How to get there. Most visitors come by road from Hanoi, by expressway to Ha Long. Van Don International Airport, opened on 30 December 2018, is about 50 kilometres from Ha Long. Boats into the bay, from day trips to overnight cruises, leave from the harbours of Ha Long.
The weather. The climate is tropical and wet, with a hot, humid summer and a cool, dry winter, and 2 to 2.2 metres of rain a year. Summer storms can arrive quickly. On 19 July 2025 the tour boat Wonder Sea capsized in a sudden thunderstorm in the bay and 39 people died.
The floating villages. Part of the floating villages’ living comes from visitors: rooms to rent, boat trips and fresh seafood.
Safety. The United States has Vietnam at Level 1, exercise normal precautions. The advisory warns of petty crime in tourist areas and of landmines and unexploded ordnance, which it says are a low risk in urban areas and tourist destinations.
Mark this place
The passport stamp for this place.
Common questions
How was Ha Long Bay formed?
By the sea flooding a range of hills. Ha Long Bay in Vietnam is a limestone tower landscape that weathered out on dry land over some 20 million years and was then drowned: most of its islands are the tops of steep towers whose plains are now under water.
How many islands are in Ha Long Bay?
It depends where the bay ends: some 1,600 by a narrower count, about 2,000 by the widest, and 989 of them have names. Ha Long Bay covers about 1,553 square kilometres of the Gulf of Tonkin, off north-eastern Vietnam.
What does Ha Long mean?
“Descending dragon.” A local legend tells of dragons sent to defend the country, whose jewels became the islands of Ha Long Bay in north-eastern Vietnam. The name itself is young: it appears in the late nineteenth century, on a French maritime chart.
Is Ha Long Bay a UNESCO World Heritage Site?
Yes, since 1994. UNESCO inscribed Ha Long Bay, Vietnam, in 1994 and again, for its geology, in 2000; in 2023 it took in the Cat Ba Archipelago and renamed the site Ha Long Bay – Cat Ba Archipelago: 65,650 hectares and 1,133 islands and islets in Quang Ninh province and Hai Phong city.
What are the notches at the base of Ha Long Bay’s islands?
The sea’s signature. Marine notches are horizontal grooves that seawater and waves have dissolved and worn into the limestone at the tide line round Ha Long Bay’s islands. In places they have been deepened into caves that cut right through to enclosed tidal lakes, such as the Ba Ham lakes on Dau Be island.
How do you get to Ha Long Bay from Hanoi?
By road, then by boat. Most visitors travel to Ha Long Bay by road from Hanoi, by expressway to Ha Long in Quang Ninh province, and board a day boat or an overnight cruise in Ha Long’s harbours. Van Don International Airport, opened in December 2018, is about 50 kilometres from Ha Long.
Do people live in Ha Long Bay?
Some do, on the water itself. Some 1,500 to 1,600 people lived in floating fishing villages on Ha Long Bay, Vietnam; since May 2014 the Quang Ninh provincial government has moved more than 300 of those households ashore, keeping some villages for visitors.
Photographs on this page
Tap a photograph to see it full size.
Photograph: Marina Lobato via Unsplash, Unsplash licence, cropped
Photograph: Steffen Schmitz (Carschten), CC BY-SA 4.0
Photograph: Jean-Marc Astesana, Halong, CC BY-SA 2.0, cropped
Photograph: Jakub Hałun, CC BY 4.0
Photograph: Vyacheslav Argenberg, CC BY 4.0
Photograph: Vivu Vietnam via Unsplash, Unsplash licence
