In January 2009, an international team of cave researchers conducted a very successful expedition to Oudomxay in Northern Laos. The most significant finding and major highlight is the exploration of the Chom Ong Cave System, which is 45km Northwest of Oudomxay town near Ban Chom Ong Village. The system stretches along a 4 km long mountain ridge. It was explored in three explorations (2009, 2010 and 2011) to a length of about 18.4 km with some small, unpromising side passages remaining.

It ranks as the 2nd longest cave in Laos and the 9th longest cave in the whole of Southeast Asia. The typical passage dimension is 20m to 25m in width and 20m to 30m in height. There are two overlaying passages, a river and a fossil passage, which are linked at one huge hall with dimensions of 100m in length, 30m in width and 30m to 50m in height.

The cave is a trough cave and could be entered with exploration equipment near the small stream inlet in the north and left at the outflow in the south. The full traverse would take about 5 hours, with additional 1 and 3 hours respectively return walking time to Chom Ong village. However, it is recommended that tourists do not attempt this traverse for now, as there are several unavoidable climbing parts and slippery river walks.

Based on the opinion of the cave exploration team, the Chom Ong Cave is one of the most beautiful and interesting caves in Southeast Asia. With its two very different passages, it has a very rare diversity. It further impresses with several huge stalacmite and stalactite formations as well as vast glittering parts and geologically interesting features (shields, floe calcite, etc.).