Ha Long Bay Cruise – Day 2 – Vietnam Travel Diary – 6

The Karsts

Hạ Long Bay, in northeast Vietnam, is known for its emerald waters and thousands of towering limestone islands topped by rainforests. 

The limestone in this bay has gone through 500 million years of formation in different conditions and environments. The evolution of the karst in this bay has taken 20 million years under the impact of the tropical wet climate.

Karst is a type of landscape formed by the dissolution of soluble rocks like limestone, resulting in features such as sinkholes, caves, underground rivers, and springs. This process is caused by slightly acidic water, typically rainwater, seeping into cracks and dissolving the bedrock over millions of years. The term “karst” originates from the Karst Plateau in Slovenia and the surrounding region, and these landscapes are found globally, covering about 10-11% of the Earth’s surface. 

Among the 1,969 sunken limestone towers submerged in the indigo waters of Ha Long Bay are a series of ancient caves and grottoes – many of which remained unexplored. To date, there are 59 caves listed on the official registry (this includes the most recent discovery of 23 ‘new’ caves), all of which have a special belonging in Ha Long Bay’s distinctive ecosystem. Undoubtedly the most famous of them all is Sung Sot Cave, which has rightfully earned its near-legendary status among visitors to the world-famous bay.

Day 2, commences with Tai Chi lessons at 0630 on the top deck of the cruise boat. Weather permitting, sun rise visuals are pleasing. After a sip of coffee/tea with cookies, we proceed on a smaller boat to Sung Sốt cave.

Sung Sốt cave

Sung Sốt cave is an old phreatic cave. It means “Grotte des Surprises”, or Surprising Cave, because of its ‘surprising’ beauty. It is on Bo Hon Island. From its truncated entrance chambers on a ledge high on the cliff, a passage of more than 10m high and wide descends to the south. It takes an hour to walk through the cave.

Sung Sot cave is the largest, perhaps the most renowned, and likely the most visited of all. 

There’s a small dock at the bottom of Bo Hon Island, where you’ll dismount your boat and begin the climb up 100 or so steps to the mouth of Sung Sot Cave. The cave covers a staggering 10,000 square meters (that’s twice the size of the White House if that’s anything to go by).

 The interior is separated into 2 caverns, the first of which is a small amphitheater type of space connected by a small passageway to the larger cavern next door, which is big enough to hold 1,000 people or more. The entire cave is bestrewn with stalactites and stalagmites, which serve as endless material for the legend and ‘lore of the area.

After the visit, it is time to pack up, checkout and loiter around the boat till it docks back.  

Here is my video.