In 1992, members of the British Expedition, and British Cave Research Association (BCRA) decided to try and find the source of the Chay River. According to maps, this emerged from the limestone, so there should be a cave there. Helped by the local people they took a boat to what is now Tro Mong Ranger Station (opposite Dark Cave). From there they trekked for the rest of the day and camped for the night. Their local guides Mr Khanh (not Ho Khanh) and Mr Nguon, led them to an entrance where the water came out. This entrance was known to the locals as Hang Vom or Arch Cave.
Following the river into the cave they swam across large underground lakes. After about 1.5 kilometres they reached a place where daylight was seen through a shaft in the roof. They called this place ‘The daylight beckons’. At this point on the left they could see the start of a big dry passage. Leaving the river they started exploring and mapping this passage.
Over the course of the 6 week expedition, this passage was explored for 3.5 kilometres. The passage emerged into the jungle at the base of a cliff. At this time they had no way of knowing where the entrance was, and they could see no path through the jungle, so they retreated back to the Hang Vom entrance. The jungle entrance they called Entrance number 2.
In 2005 a local man Mr Ngo Phong took expedition members to a new cave, Hang Me Bon Con. This was quickly explored, and Mr Phong took them to a second nearby entrance. He thought this was a new cave, but the leader Howard Limbert soon recognised it as entrance number 2 of Hang Vom. The team went through the cave from entrance number 2 to the Vom entrance, with Mr Phong’s brother, Mr Liu.