Participants:	Michael Laumanns (coordinator)   Jos Burgers   Marcel Dikstra   Matt Oliphant   Nancy Pistole   Jean Charbonnel
Local Team:	Rainer Arenskrieger   Ines Seiler (GIZ)

The 2011 expedition consisted of a small team of 6 speleologists and targeted again the Tham Chom Ong System (Oudomxay Province) as well as a previously untouched new area: Sayabouli Province, which borders Thailand. The investigations were again made in co-operation with the German Development Service (DED) and the local Provincial Tourism Departments.

Oudomxay Province:
Finally, after 3 years of exploration, the Tham Chom Ong System was finished off by descending a 12 m and another 25 m deep vertical drop leading to the discovery of an intermediate cave level approximately 1.3 km in length, which connects to already known passage. The TCO System has now a new length of 17.1 km. Its ranking as the 3rd longest cave of Laos and the 10th longest cave of SE Asia remains unchanged.

Furthermore several smaller caves near Chom Ong village were surveyed, not much exceeding 200 m in length each. All together, about 2.5 km of new cave passage was mapped in Oudomxay during the 2011 expedition in 4 caves.

Sayabouli Province:
The first systematic speleological exploration ever took place in the area of Ban Keo and Ban Nathang, about 40 km south of Sayabouli town. An ecotourism project with homestay accomodation is being conducted in the small village of Ban Keo, which served as a base for the 2011 expedition. Within only 5 days about 8.5 km of new passages were mapped in 12 new caves. Furthermore, several new karst resurgences and sinkholes were visited, providing good additional potential for another expedition in 2012 to the same area. The longest cave mapped was Tham Nam Lot - a through cave with an underground stream and a long fossil extension. The cave is about 3.6 km long. Tham Pha Khoun Houy was finished off with a total length of 1,922 m. Tham Phafah was found to be 1.3 km long and features a rare "cave ring" on the floor of one chamber.