Khammouane 2012

from february 4 to 25th



The 2012 expedition had three main objectives: the continuation of the exploration of the Nam Dôn cave system (future longest cave network in Laos), of the left bank of the Hin Boun river (where about twenty kilometers of cave passages have already been explored) and finally, of the caves at the outlet of the lower Nam Hin Boun gorges, on the Mekong side.

The expedition is now finished and 16 kilometers of new passages have been surveyed. A remarquable result since the explorations took place almost exclusively in caves already explored last year, sometimes far from the entrance.

Week 1

During the first week, the team has been hosted in Ban Na, a small village a few kilometers north of Thakhek. The Houay Saï - Khoun Dôn cave system has been extended in the north and east directions. Beyond Tham Kouan Pheung, the Bees Sinkhole cave, explored in 2011, Tham Kouan Kaohong was discovered and the large underground river that feeds Tham Houay Saï, was accessed in huge tunnels, true avenues towards the sinks further east and north. The length of the Nam Dôn system has been rised from 21 to 27 km, strengthening its position as second longest cave network in Laos, behind the Nam Non system (31 km).

Week 2

Then the team has migrated to the middle Nam Hin Boun valley and settled at the confortable Sala Hin Boun. On the river left bank, a series of large caves was waiting for us.

In Ban Gnang, the exploration of Tham Lom has been complicated, since the cave was systematically opposing climbs and shafts to our progression. Despite the obstacles, the surveyed length has been increased to 5890 m (270 m vertical).

Further west, in Ban Vang Pia, Tham Biéo, where the 2011 explorations had been stopped on... nothing, was extended only by 600 m. The new passages all end up in already known parts of the cave. The potential for continuation is tiny.

In between, near Ban Houay Sai, climbs in Tham Nam Peo did not give the expected results. The cavity is close to two kilometers in length, but its continuation will be the cave divers privilege. Several beautiful sumps and a nice resurgence have been located.

Tham Vang Phouang, formerly Tham PCF (2010), was continued. The large shaft interrupting the main gallery, 200 m from the entrance, has been bypassed using an impressive ledge which gives access to over one kilometer of virgin passages. Wind is everywhere. Exploration has been stopped on the edge of several shafts.

The last day, Tham Shouan Kao, the cave of the Ancient Garden, was found at the cliff foot behind a squeeze from which a violent wind was escaping. It gave access to 300 m of large fossil passages, before opposing a P20 shaft to our progression. To be continued next year...

Week 3

Finally, Ban Nakhok, near Ban Thonglom, has hosted the team during the expedition third week. Just outside the beautiful gorges of the Hin Boun river, several large caves had been partially explored by the Spélaos 2011 friend team led by Gilles Connes. Tham Deng, a cave exploited for its phosphate deposits, has been explored over 4260 m, and connected to the neighbouring Tham Tay. Further east, Tham Heup and Tham Thê have been (re)surveyed (1310 m and 2950 m respectively)

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