Khammouane 2015 - K15

Février-Mars 2015


Executive Summary

With 17 participants from France, but also from Germany, USA and Australia, K15 (Khammouane 2015 expedition) has been one of the largest caving expedition ever conducted in Laos.

Once again, the huge cave system of the underground Nam Dôn river (TKDHS) has been the focus of the Explo-Laos team during three weeks. On the emergences side, two caves, Tham Khoun Dôn (TKD, cave of the river Dôn spring) and Tham Houay Sai (HS, cave of the Sand Stream) connected since 1998, are the main entrances of a vast sub-horizontal cave network, partly labyrinthine. Since 2011, our explorations have extended the development from 12 to 39 km. This year, a new river channel was discovered with a temporary stop on siphon, and we have started the opening of the Blue System in the extreme east of the cave, behind the Kaohong Guardian (see Spelunca XX). Two new entrances have been discovered, one at the top of the system (+270m), the other at its eastern extreme, in the cave of the Canopy Raft discovered last year. This new opening, narrow and defended by a snake, opens in a deep sinkhole. On the opposite side, the cave keeps going, but the passage is closed by a boulder choke. TKDHS has now 22 entrances. Many question marks were removed, two additional kilometers have been mapped, and it will soon be time to leave some space for the cave divers.

Further north, the large Ban Vieng polje is drained by two major sinks that feed the TKDHS river. The exploration of Tham Kagnung, a permanent active sink, has been resumed. Thirteen years ago, explorations had stopped on a siphon (dev. 1.6 km, Mourte et al., 2003). Only a partial topography (500 m) was published in 1998 In a CREI report. Alternating climbs with boating and swimming, the development has been increased to three kilometers. The cave is heading south, towards the TKDHS terminus. After climbs almost everywhere, we fear that on this side of karst, only divers will now make further progress.

The second cave is again called Tham Houay Sai. This is a temporary sink, active only during the rain season. The exploration has been considered as "finished" since 2002 (Moutre, 2003). Climbs allowed to bypass the terminal siphon and rejoin the river in a large gallery which runs NW towards the TKDHS terminus. A new sump stops temporarily the progression. There is still some work before the junction for which we have been working for several years to be effective. Tham Houay Sai sink develops now 10 km. Meanwhile, a new entry, named Cobra II, especially comfortable to rapidly join the terminal area of ​​the cave was discovered from the inside.

Only 1.3 km are left now to connect the three caves and thus create a through-cave of over 100 km of extension. A long distance would you say ? Not really, because in Laos, cave penetration can be very rapid. A little further north, in just one hour, we surveyed 800 m in the giant gallery of Tham Simali, a sacred cave whose residents have agreed to allow us a temporary access after years of discussions and patience.

Regardless of that substantial work, a new cave, Tham Heun, a stream source blowing a strong fresh wind, was explored at the request of local authorities. In four days, two kilometers have been surveyed, with a stop by lack of time. Unlike the case of Tham Kathoung in 2013, the progression is too technical for a tourist operation of the cavity to be considered, but the possibilty of continuation is still serious.

Several exploration sessions in lost valleys brought a dozen of small-scale cavities. There is still much to do.

Two US researchers have joined the team this year to study the paleoclimates of South-East Asia, recorded into stalagmites. Several interesting sites have been identified, and sensors (stalagmometers) have been installed. To be continued in 2016.

The team is well integrated into the local community and, as every year, petanque tournaments, football, film presentations (photo) helped to reinforce the mutual trust.

In the expedition late phase, on the sidelines of Bacis, traditional goodbye ceremonies, the team was invited to participate in the local festival, and at that occasion, the most adventurous could launch "their" own rocket.

Film show in Ban Luang. The whole village is here!

True Explo-Laos kids at the Ban Vieng rockets festival !

Many thanks to the villagers of Ban Na, Ban Vieng and Ban Luang, who welcomed us once again this year, as well as Mr. Panya Chantallah, head of the Tourism Development office in the province of Khammouane.

The overall expedition organisation was entrusted to Green Discovery Laos.


Thierry Alibert

Eric Ardourel

Jean-Luc Aubert

Terry Bolger

Annie Caillault

Serge Caillault

Lubin Chantrelle

Charles Ghommidh

Michael Griffith

Florence Guillot

Laurent Guizard

Kathleen Johnson

Denis Langlois

Stéphane Maifret

Jeremy Robert-Degude

Richard Quintilla

Helmut Steiner

  1. 17 participants

Clubs participants

Camberra Speleological Society


Club Omnisport de Valbonne


Groupe Ulysse Spéléo

GSM Fontaine

GS Montpeyroux

Northeastern Cave Conservancy


SC Montpellier

SC Souillac