Doline 1 - Watch Out For Dinosaur

Doline 1 of Hang Son Doong is an area where the ceiling had collapsed, creating a skylight connecting to the outside. According to the survey of the British caving group, the 1st doline has a depth from the cliffs on the surface to the river at the bottom of the cave of 449 meters. This is also where the underground river disappears inside Son Doong Cave.

During sunny days at Doline 1 - Hang Son Doong, there are spectacular sunbeams shining into the cave from 11 am until 1 pm. From January to March especially, the sunbeams go deep into the cave passage, lighting up the huge arch of the cave. However, whenever it is sunny throughout the year, the Son Doong sunbeams are present and provide one of the iconic views in the cave. The Son Doong sunbeams and the mist which is formed by the temperature difference between outside and inside the cave create a unique magical scene that is like nowhere else. Many people think that this place is like another planet, some say it is like the Avatar movie.

Doline 1 - Watchout for Dinosaur.

Doline 1 - How it formed

The first doline is located about 3 km from Son Doong entrance. This is the first doline inside Hang Son Doong Cave. The cave passage which was formed by the underground river running through the cave passage, created a very tall high passage. The layers of limestone in the area of Watch Out for Dinosaurs are quite thin, and therefore not very strong. These weaker layers then collapsed, leaving a long narrow hole in the roof, although the passage underneath is still very big. The widest point at Doline 1 is recorded as 125 meters on the Son Doong map. When the sunlight from outside hits the narrow opening, they create magnificent scenes inside the cave. As the sun crosses the sky outside the cave, the sunbeams cross the passage inside the cave.

Doline 1 - Watchout for Dinosaur and the sunbeam shining in from the outside in Spring.

Doline 1 - Why Watch out for Dinosaurs

As you climb up the hill into the first doline, you will enter a world unlike anything you have seen before. The original explorers were having a conversation about dinosaurs, and when they climbed into the doline a chance remark ‘watch out for dinosaurs!’ became the name for this unique location. It is easy to imagine that crossing a jungle deep inside a cave, you might find anything.

An iconic view of Doline 1 in Son Doong, you can catch this moment if you are lucky.

The Wedding cake

Inside the first doline in Son Doong there is a large stalagmite. Due to the regular waterfalls on top of the stalagmite, the surface is quite flat. It is however still composed of calcite in the form of rimstone or gour dams, and does contain cave pearls.

This rock has been named by tourists as the Wedding cake. This is an iconic location and almost all tourists who join the expedition want to take a memorable photo here. It was here that part of Alan Walker's music video named Alone Part 2 was filmed. This is also where the famous American MC Ginger Zee uttered that it was like a scene in the Avatar movie.

Wedding Cake in Doline 1 Watch out for Dinosaur.

For safety and conservation reasons, when arriving into the first doline, the group of 10 has to split into smaller groups, in order to take turns to go onto the Wedding cake to enjoy the grandeur and take photos; There is a viewpoint looking back to the first campsite in Son Doong Cave - The Level Playing Fields; Or simply stop and admire the leaves falling slowly from the top of the doline, or small waterfalls falling from the ceiling. There is an amazing variety of plants which have adapted to this challenging environment. Sit and think about this amazing place, and how it is formed entirely by nature.

The Green Gours

After the first doline as you move towards the Garden of Edam, you will see some unique formations. You will pass a huge expanse of Phytokarst, a rare cave formation. Looking ahead you will see the whole of the passage is filled with gour dams. Where the sunlight touches these formations, microscopic plants like algae can grow, hence the formations turn green due to the plant life they support. For many they are reminiscent of the rice terraces in Northern Vietnam. To avoid damage, the footpath takes guests around the terraces, to a flat area which is the lunch stop. Whilst having lunch, you can enjoy a cup of tea or coffee and also absorb the wonders of nature which surround you. Take your time and take some pictures; many guests find it hard to tear themselves away from this unbelievable place.

The Green Gour.

The Oxalis Experience.


  • What is causing the erosion of the Son Doong cave?

    The main reason is the high quality of limestone in a single solid bed, and a large river flowing through the cave.

  • How did skylights form in the Son Doong cave?

    There are two doline (also known as skylight) in Son Doong. Doline 1 and Doline 2. The first doline Watch out for Dinosaur is formed by river water eroding away the limestone underneath the mountain. The cave here has thinner beds of limestone hence the collapse. The second doline collapse is caused by the junction of two main faults, one from the main Son Doong passage and the other from the Alcove passage.

  • What kind of rock is Son Doong made of?

    Like many other caves, Son Doong is formed of limestone. Limestone is a sedimentary rock that was deposited on the sea bed many millions of years ago. It is composed of calcium carbonate, which is derived from bones and shells of dead sea animals. These bones and shells fell to the bottom of the sea, where they built up in layers. These layers were compressed really hard to form a type of rock. Movement of the earth’s tectonic plates and lowering of the sea levels has caused the limestone rock to be raised up forming mountains and plateaux. The rocks in this area are 350-400 million years old. Also, the purity of limestone here is one of the highest on earth, which is over 99% purity.

  • How many entrances are there in Son Doong?

    There are only 2 accessible/passable entrances in Son Doong.

You may like

Whether you prefer long treks, camping in a cave, sleeping under the stars in the jungle, swimming underground in river caves, explore the huge dry caves or just taking an exploratory day trip, Oxalis Adventure Tours can provide the right amount of adventure just for you.

Multi-day packages

Overnight tours

Day tours

Family tours