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Photo: Jérémie B., CC BY-SA 4.0 via Wikimedia Commons
If your budget doesn't quite stretch to Son Doong cave, Oxalis also offer 1-4 day trips to Tu Lan and Hang En caves. They seem to have a monopoly on the overnight cave trips, but they do have good English speaking guides. Prices start around 5.5M dong, limited or no trips during the rainy season from September-December. Beware of tropical storms when visiting the Hang En cave, it is prone to flash flooding.
Hang Én, occasionally referred to as Én cave in English, is a cave in Phong Nha-Ke Bang National Park, a UNESCO World Heritage Site. Én is the third largest cave in the world, after Hang Sơn Đoòng in the same national park, and Deer Cave in Malaysia. The cave has its own jungle, waters, beach, and climate. There are three known entrances to Hang Én.
© OpenStreetMap contributors
Dark Cave
A real adventure cave, still without the lights and large tourist groups to spoil the experience. Explore this spectacular cave on a National Park tour or independently, and after kayaking across the river, enjoy swimming through the cave with your headtorch leading the way, then explore a side passage. Hang Toi is a wonderful and very accessible example of the beautiful caves that are found throughout this region.
Discovered in 2016 by a local man, this cave has the potential to be the 2nd biggest cave in the world. The first tourists experienced this cave in 2017. Green Land Tours is the only company that offers access to each of the cave's two entrances. The tours are led by the man who discovered the cave and spent 2 years exploring it. The Ruc Mon Cave is named after the indigenous people who made a home at the entrance until the 1980s. The cave is 17 km long, with one entrance in Phong Nha-Kẻ Bàng National Park and the other at the border of Laos. This cave has the potential to be the second biggest cave in the world, following the first biggest cave also located in a Phong Nha. One of over 300 caves in Phong Nha Ke Bang National Park, this cave is probably the least-explored of the many caves open to tourists.