Reseau de la Diau

This year a group. of us from Cave & Crag and BUUS visited the Reseau de la Diau intent on doing the
classic through trip. The Diau is a large and impressive river cave situated at the base of the Parmalan plateau near Thorens in the Annecy region of France In 1976 a top entrance was discovered, the Tanne du Bel Espoir, and thus a through trip, reputed to be one of the finest in the world, was created. From the top entrance to resurgence is a distance underground of about four and a half kilometres. The depth is 2000ft and involves descending some 25 pitches.

On reaching the campsite at Nantizel, we encountered a large contingent of Chelsea members with caving plans identical to our own. Negotiations between the two groups took place, and cooperation in rigging and de-rigging the cave was agreed.

The Tanne du Bel Espoir, 5000ft up on top of the Parmalan plateau, is notoriously difficult to find Chelsea had enlisted the help of the local Annecy club who had shown them its location. Chelsea had the marked the route across the bare limestone clints to make finding the entrance an easier task; a wise precaution as the plateau was in mist most of the. time.

We did a recce trip in the Grotte de la Diau, then ferried tackle up to the top entrance. Chelsea rigged the first four pitches of 33, 28, 16 and 37 metres. On the following day, our group rigged the next five pitches, all very muddy ones; down to the Salle des Rhombaedrès. The trip out was quite an epic as SRT gear clogged up on the appallingly muddy ropes.

After a rest day we were all to do the trip through to the Diau. The first party rigging the rest of the cave through to the Diau, a second, smaller team of Chelsea members following, and our party going in last and de-rigging the cave as we went down — save for the upper pitches which could be de-tackled from the surface later.

Chelsea went in early on a fine, sunny morning. By midmorning the weather was changing, and by midday, when we were due to go in, it was raining. As the Diau floods fiercely, we decided to postpone our trip a day. Instead we retired to the excellent inn at the end of the track that leads up onto the plateau, and discussed the cave with the proprietor over large mugs of coffee. Fortunately, the threatened storms did not arrive, and after a couple of hours of light rain the afternoon and evening turned out fine. Al1 the Chelsea lads got through OK, so our group decided to go through on the morrow.

Below the Salle des Rhombaedres, a massive boulder-strewn chamber, is the Puits de Echoes, the longest pitch in the cave and split into three sections of 21, 6 and 45 metres. A really superb shaft with spacious ledges on route. Below, one in the Affluent des Grenables, 1500 metres of narrow, winding streamway with numerous short pitches and cascade’s — all very attractive and sporting caving. The final pitches are 8, 30,16 and 12 metres. Clambering over a huge roof fall then leads to a long muddy tunnel that emerge into the vast gloom of the Diau river. Shouldering tackle bags we made our way downstream towards the entrance, two and a half kilometers away.

Large river galleries deep dark water; the massive Chaos Chamber; deep, wide, si1ent canals; the interesting fossil Labyrinth series; more deep water wire traverses; cascades; the roaring Spinning Top; the stemp1e climb; the journey through the Big Blower; more deep, cold water; fixed ladders in the Salle de la Carene; and finally struggling over the boulders of the vast entrance chamber, to be greeted by. a sky full of heavy rain, thunder and lightning. Fortunately we were out before the rain affected the level in the Diau. Seeing the entrance arch lit in silhouette by lightning was a memorable sight.

Conclusions? The trip had taken the main de-rigging party of six people l0 and a half hours. Whether or not rigging the cave is necessary ( for safety escape should the Diau become impassable) is debatable. Exit from the Salle des Rhombaedres would be very difficult on SRT alone. The cave is rigged for double-line through trips, and provided one has done a recce in the Diau first, route finding is no problem. Watch out for the weather though. In all, an excellent trip spoilt only by the muddy upper pitches.

Dave Irons.

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