Son Doong Cave (Vietnam)

Son Doong Cave, or Tham Sein Dong, the world's largest cave located in Vietnam, is situated in Phong Nha-Ke Bang National Park, Quang Binh Province, near the border between Vietnam and Laos. Within this national park, there are still many areas that explorers have not reached, and exploration is only possible during the dry season. Son Doong Cave (Sein Dong means 'Mountain River Cave') in Vietnam is an ancient cave estimated to be 2-5 million years old, hidden within a valley. It was discovered by a local in 1991, but no exploration took place due to the villagers' fear of strange sounds coming from inside the cave. It was not until 2009 that a British expedition team ventured in and found that the strange sounds were caused by the flow of water inside the cave. Furthermore, the cave's interior boasts an environment that is breathtakingly stunning, like another world untouched by humans, with its own jungle, stalactites, stalagmites, and cave pearls. The cave was opened to tourists in 2013, and visitation is limited to only 500 people per year. Those who wish to visit must book a year in advance. The cave is open from January to August (March to May is recommended as the best period). The entrance fee is a 4-day, 3-night package, plus one day for the journey there and one day for the return, costing $3,000 (approximately 150,000 baht) per person. To ensure the safety of travelers, there is a minimum age requirement of 18 years and above. The difficulty level of the adventure in this cave is considered level 6, which is quite challenging. The trip includes a total of 17 kilometers of trekking, 8 kilometers of caving, and a 90-meter cliff climb. The trip organizers provide guides for assistance throughout the trip, porters for carrying luggage, and meals for every dining occasion. In 2019, explorers discovered that Son Doong Cave might be even larger than previously thought, with the discovery of a new underwater tunnel connecting Son Doong to a massive cave called 'Hang Thung,' which has a volume of 1.6 million cubic meters (Son Doong Cave has a size of 38.5 million cubic meters). This is considered a remarkable natural wonder. Moreover, to date, only less than 30% of Son Doong Cave has been explored, leaving a vast amount of secrets still waiting to be discovered.