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BU56 - Puertas de Illamina (-1408 m.)
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If the shivers don?t run down your spine when you hear the magic word  "BU56", then you are 1) not a caver or 2) a speleological barbarian.

The BU56, situated in the Spanish Pyrenees has been discovered nearly 24 years ago but it still remains a mythical cave. Once it was the deepest of the planet (-1408 m) on even now it is still a cave of which we all speak with a lot of respect.

And why is the BU56 so special?

Caves of over 1000 meters deep are, these days, not exceptional anymore: there are over 50 of them.   But in most cases, these are vertical caves in which you go down on a rope; all the way to the bottom.  Underground progression in such a cave, becomes a technical  thing, and climbing out of such a cave is quite monotonous; hanging on a rope for 15 hours or more is ? just boring.

But in some caves, to reach the magical depth of one thousand meters, you must progress for many kilometres and deal with many obstacles such as waterfalls, pitches, big piles of boulders, narrow and difficult winding meanders. Roaring underground rivers, beautiful flowstone formations, giant underground rooms are the icing on the cake in such caves.   Often they have multiple entrances which offer extra possibilities such as through-trips.  These are the caves we all love.

Gouffre Berger (-1271 m), Réseau Jean-Bernard (-1602 m), Systema Badalona (-1050 m), Réseau de la Pierre-St-Martin (-1342 m) are some of those fantastic and ?complete? caves, that are on every cavers? wish-list.   

And then? there is the BU56.

Richard Maire, one of the original explorers, near the entrance (Paul De Bie, 2003)The BU56 is one of those ?great? caves. But, it is yet different from the others.

There is only one entrance known.  You go in there, and you?ll have to go out there.  No cheating is possible; no through-trips.  And the bottom of the cave, or better the terminal sump at a depth of -1325m, is about 8 kilometres away from that entrance? so you are heading for a 16 km trip.

The entrance? means 400 m of pitches, with some long and very narrow meanders in which you will loose hours and a lot of sweat.

The entrance?is situated at an altitude of 1980m and you need a very long walk (about 3 ? hours) and a +900m climb to get there.

Once you arrive at the bottom of the pitches, you find an underground river of exceptional dimensions. The more you go down in the cave, the bigger it gets until becoming a raging river in which progression gets nearly impossible.  In Canyon Belagua at a depth of  -1200m, you have to traverse 20 meter high above the thundering river, over a distance of nearly 200 m, on a narrow ledge.  Around -1250m the river, this river (1m?/sec) crashes down in a series of big waterfalls.  The discoverers of the cave wrote about it: ?Emotion guaranteed".

The progression in the cave is no Sunday walk. The river alternates with big and chaotic galleries, in which you climb up and go down huge piles of boulders all of the time.   In Salle Roncal at -750 m, the pile of boulders is no less than 80 m high (that?s as high as a 30-story building!),  and once you are up, you have to go down the other side ? for an incredible 110m!  When taking all these ups and downs into account, the depth difference you make in the cave is almost 1600 m!

Most of the classic ?big? -1000m caves, such as Gouffre Berger, can be done in one (long) trip by a well trained team in less than 20 hours.  In case of the BU56, this is not possible.  If you want to make it in one trip, then you are heading for a 35 hour trip or more!   That?s why most teams split the trip up in parts, making it a two or three day trip.    But, sleeping in  a cave means taking a lot of extra stuff with you: food, sleeping bags, tents and so on.

In short: a trip to the bottom of the BU56 is a serious undertaking.

Finally: the cave is located in the world-famous Pierre-St-Martin area, and so it is closely related to the history of the PSM? a library full of exciting and breathtaking stories.  It is evident that a caver who loves the PSM, cannot ignore the BU56!    And? in caving club Avalon, there are quite some people who lost their heart in the PSM .

Some history

The entrance is discovered by Jean-Fran?is Pernette  and I. Ortilles in 1979. That day Pernette reaches a depth of -92m after passing the extremely narrow meander N.  In the following two years, expeditions follow in which many famous French cavers participate; such as J-F Pernette, Richard Maire, Serge Fulcrand, Gerard Bouteiller, Georges Marbach.  They push the cave to a depth of -1338 m; making it the deepest of the world.   Fred Vergier dives the terminal sump of the cave and two following sumps.  In 1986 and 1987 a Bulgarian expedition dives three more sumps, stopping before sump nr 7.  This fantastic achievement brings the depth of the cave to -1408 m.


The pitches( from "Sp?? Sportive ?la PSM"  by Doaut, Pernette, Puisais - Edisud 1985)The entrance pitches go from 0 to -387m. There is a serious obstacle at -80m;  the "Mééndre N"  which is 60 m long and very narrow.   At the base of the pitches (-387m) begins "Mééndre Oprimido"  which is over 300 m long and is so difficult that you need +/- two hours to get through.  Once through the meander, you arrive near -452 m in a gallery with boulders.  This becomes bigger and bigger and soon you find the river that runs on the ?primary socle? of hard schist rock.  The progression is not easy, many sumps have to be avoided by lateral or superior passages, often narrow and time-consuming. 

For some waterfalls you need to use a rope and so you finally arrive in the first big room of the cave: Salle Arcaute at -575 m. There you go down a 19 metre pitch and continue to follow the river that thunders down steep toboggans.   Near -700 m the gradient becomes less steep; but the flow rate of the river (more than) doubles because of a big inlet, coming from Sima de la Hoya del Portillo.   Then the river flows softly in a wide and high canyon. A 30 m long lake can be avoided by taking a low and muddy shunt at the left.   Then it disappears between the boulders, which we climb up to arrive in the biggest room of the cave: Salle Roncal.  This room is over 500 m long and about 50 m wide. A giant and very steep pile of boulders, over 80 m high on the East side,  and 110 m on the West side, is a tough obstacle to take!  Near --780 m, Salle Roncal narrows, the floor becomes flat: this is the usual place to camp.   Further on, we arrive at a very decorated balcony dominating the thundering river.  We go down a 20 m pitch and enter Canyon Roncal.   In this very narrow canyon, the progression is very spectacular and wet, and if water levels are high, even quite difficult!

The river in the BU56 (JF Pernette, Rivi?es sous la Pierre, Nathan 1983)After 250 m of most exciting ?white water? caving, a 10 metre pitch besides a powerful waterfall brings you to Salle Paquiza. This is the most decorated room of the cave with hundreds of three metre long straws.  This room, continues into other big rooms and galleries such as Salle Ukerdi, enormous and very steep!  Near -1000 m however, the passage suddenly lowers and becomes very narrow.   The only way on is a real squeeze, situated just at the waterlevel.  This passage floods quickly, up to 10 metres of height, when it rains outside!  This is really the point of no return.

Then, another series of big rooms and galleries... Belagua Gallery is beautifully decorated, with big ?stairways? of flowstone and gour pools where you walk on.  A final big inlet, Rio Linza, again increases the flow rate of the river, which is meanwhile swollen to an average of 1 cubic metre per second!  Salle Linza (80x80m) and Salle Maz. (120x50m) are quickly traversed. Then the river crashes down into Canyon Belagua.  It is impossible to progress in this canyon because of the raging river.  One must traverse on a ledge, 20 metres above the river, for the incredible distance of +/- 200 metres.  Secured by handlines, tied to stalagmites, high above the roaring river, this is one the most frightening and impressive passage that can be encountered in a cave at such a depth (-1200 m !)  Finally, a 17 m pitch puts you back into the river again.   Another wild water part follows, untill finally the water goes down, with unbelievable power, two consecutive waterfalls, 18 and 16 metres high!  They can be avoided by a fossil upper level ( Galerie Lapazarra) leading to the terminal sump of the cave at the depth of -1325 m.   5 other sumps follow, leading to a 7th, non-dived sump at -1408 m.   For us, normal cavers, the only way on is?.back to the entrance? 8 kilometres away and 1325 m higher!


From "?la D?ouverte des Gouffres de la PSM, JF Pernette, SNMJ Pau 1982

The SC Avalon ?BU56 project?

After having made several serious caving trips in big caves situated in Pierre-St-Martin area (late 80?s and beginning of the 90?s), such as Pierre-St-Martin, Couey Lotge, and Lonn?Peyret); the BU56 seemed like the next logical step to take for our club.

Indeed, about 10 years ago Annette and I played with the idea to bottom that BU56.  But the project never got off the ground and ended up in the freezer?

In 1997 we ?rediscovered? the PSM-mountains once again, with a bottom trip in the Anialarra System (-648m). And this time we stayed, year after year we continued exploring the Anialarra cave and its giant and chaotic galleries.Near the entrance of the BU56 ( Paul De Bie 2003)

In the meantime, we had become ?old?, mid forty, but much to our surprise those PSM-caves were still a piece of cake for us.   We realized that we still had the potential to do the BU56? but it was also clear that if we waited another 10 years, it would be too late!   So, in 2002 I again suggested to my fellow clubmembers that we should go and bottom that BU56 cave once!   And yes, some others immediately agreed: Mark Michiels, Rudi Bollaert  and Mario Lebbe would join us in this ambitious project..

We thought it would be better to have an even number of participants, and if possible somebody that had already done the cave.  We ended up with Koen Mandonx of Spekul caving club, who we knew very well because he had been an Avalon-member for several years. Koen had once done the cave(20 years ago!), but only to -1000 m; and he was very keen on taking a revenge on the cave and do it all the way to the bottom this time!

The ?administrative? side of our project was soon settled, thanks to our ARSIP-friends that quickly arranged the permissions form the Spanish authorities (the cave is situated in a nature reserve).   We also fixed the date: we choose mid-September , because a) in August we had our annual Anialarra-expedition and b) the BU56 is very flood-prone, and in general September is the month with the least rainfall.

We decided on our strategy. It would be a three-day trip  (after two days of gear-carrying and rigging)

Day 1: to -800 (camp in Salle Roncal)

Day 2: from -800 to the bottom (the sump is at -1325m) and back again to Salle Roncal

Day 3: from Salle Roncal to the exit.

Then another two or three day for de-rigging and carry all gear down again

So, one week should be enough? but there was no possibility for resting, or waiting in cave the weather was bad.    It looked as it was going to be a very tough week  

The underground campPrototype of our lightweight tent (Paul De Bie 2003)

Of course, this plan means a lot of gear. Underground camping means: sleeping-bags, a lot of food, cooking gear, a tent etc?  After a lot of thinking we decided to use two very compact and light home-made tents, made by Annette. Each could shelter 3 persons and had only a weight of 1,5 kilograms.   We tested one of these tents in the Anialarra-System, a similar cave as the BU56 and we had a comfortable night. Condensation hardly occurred, and with a candle we could easily raise the temperature in the tent from 4 to 8 degrees Celsius.

Anyway, needless to say that each participant will be carrying a very big and heavy tacklebag when going down the BU56?  

What now?

At the end of our  Anialarra-expedition, in August 2003, we already went to the entrance.  We were guided by two legends of the PSM-area: Michel Douat and Richard Maire.   For several hours we walked through a magnificent landscape, to arrive finally at the entrance, on which the number ?BU56?, painted by J-F Pernette  in 1979, is still visible. Of course, that day we already carried a lot of gear with us, such as 450 metres of rope, two tents and so on.

Within one month or so, you will be able to read in our Hot News, if we succeeded in our plan to bottom the BU56 in only one week.

Paul De Bie

August 2003


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