Tresviso 2024

The 2024 expedition, to Tresviso, will shortly be returning to the UK after a very wet and miserable 2 weeks of weather but some excellent caving.

Overview & brief history:

The Picos de Europa is a range of mountains 20km inland from the northern coast of Spain, forming the westerly extension of the Cantabrian Mountains.

It consists of three main ranges, the Western, Central and Eastern Massifs.

• The Western Massif (Cornion) is to the west of the Rio Cares and has been explored by various clubs including Oxford University Caving Club (OUCC), Seccion de Espeleologia Ingenieros Industriales (SEII), York University Cave and Pothole Club (YUCPC), Sociedad de Espeleologia Geologicas (SEG) and Speleo Club de Paris (SCP).  This includes the area under exploration as part of the Ario Caves Project and includes the Pozu Xitu – Cueva de Culiembro system (-1264m)
• The Central Massif (Urielles) is between the Cares Gorge and the Rio Duje and has been mainly explored by the Speleo Club de Seine (SCS), Spekul and IE Valencia.  Caves in this area include Sistema del Trave (-1441m), Pozo de la Cornisa (-1507m) and the deepest cave in Spain, Sistema del Cerro del Cuevon (-1589m)
• The Eastern Massif (Andara) is to the East of the Rio Duje. Lancaster University Speleological Society (LUSS) were exploring the Eastern Massif from the early seventies to 1987 with the help of SEII, before several Spanish clubs, including AD KAMI, GE Flash and Tracalet, took over exploration from the early 1990’s.  The major caves in this area are CS-9 Torca de Jou Sin Tierre (-1203m) and Torca del Cueto de Los Senderos (-1169m) and the main resurgence, Cueva del Nacimiento(+535m)

It was the Eastern Massif that drew the attention of LUSS in the early 1970s. In the early years exploration was mounted from the mountain village of Tresviso and exploration was dominated by the resurgence cave Cueva del Nacimiento (Cueva del Agua) located at the foot of the mountain range.

The resurgence flows into a canal that contours the Urdon gorge with an average flow of 2 m3/s and the passages behind the resurgence lead to >12 km of surveyed passage and a height gain of over +535m.  The catchment is some 40 km3 and includes caves such as Torca Jou Sin Tierre (CS-9) at -1203m deep and Torca del Cueto de Los Senderos (Sima 56) at -1169m deep.

In the late 70’s LUSS pushed Cueva del Nacimientoto around the 11km and +300m mark, but after several years the cave was abandoned as all the major routes sumped and no continuation could be found. LUSS then turned their attention to the Andara region higher up the mountain range and sought caves that would drop into the Nacimientosystem and hopefully create a record-breaking >1500m traverse.

They found several deep caves around this ‘top camp’ area; Sara, Tere, Flowerpot, Dosser’s Delightand Sima 56were all pushed to respectable depths, but a connection remained elusive.

LUSS and then SWCC spent some time diving the sumps in Nacimientoand later 90’s trips concentrated on the heavily wooded Sierra del a Corta region, looking for a potential middle entrance between the resurgence and the deep caves at the top of the mountain range.

The Spanish clubs, starting in around 1993, based themselves out of the nearby village of Bejes and gradually explored out towards the same area as LUSS, sometimes discovering new ways on in existing caves or finding new deep systems, culminating in finding the deepest in Andara, CS-9 Torca de Jou Sin Tierre (-1203m).

In 2010 UK clubs, featuring ex-LUSS cavers, started returning to area, exploring the furthest reaches in Cueva del Nacimientoonce more, and re-visiting some of the deeper caves, as and when caving numbers allowed.  Collaboration with some of the Spanish clubs became the norm and the Tresviso Caves Project started, a joint undertaking across numerous UK and Spanish clubs.

The overall aim remains the same, a connection between one (or many) of the deep potholes to the resurgence, creating a cave system in the top 10 of worlds’ deepest caves, the deepest in Spain and potentially one of the deepest through-trips in the world.

The depth potential to Cueva del Nacimiento, at an altitude of 470m, from a selection of the major caves on the Andara range:

One of the main challenges the expedition faces is that most of the deeper caves have not been visited since the late 70’s to early 80’s.  Although surveys and descriptions exist (of varying quality), there is no way around the fact that those caves will need re-exploring and re-rigging, just to get to the previous limit of exploration before any new exploration can begin.  This requires a tough sell of repeating old work before getting to the exciting stuff!

Objectives

The expedition has several goals.  The following are a few selected objectives:

Cueva del Nacimiento

• Far Upstream Sump – support of Chris Jewell’s dive attempt on the sump
• Shepton Mallet Matador –  leads in chamber at end of cave
• Dan’s Big Room – unexplored section of maze in area of Dan’s Big Room and Winter Gardens
• Scrambled Egg Chamber – avens and leads above the Far Upstream Sump

Cueva C29 (Torca Brana Espina)

• Ongoing passage at end of newly discovered cave (-450m)

Cueva Concha Vies

• Continuation of leads at limit of current exploration

Cueva de la Marniosa

• Downstream Sump Bypass –high level leads above stream
• NCC Series – upstream climbs above the stream
• HMK – undescended muddy pitch in inlet

The initial set of objective quickly changed once weather and opportunities dictated and focussed on the following:

Far Upstream Sump dive

• Old Leads near Winter Gardens
• Cowshead Cavern dives
• Torca LaBarga