phil
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Tresviso 2026 – Rope Sponsorship
Overview & brief history:
The Picos de Europa is a range of mountains 20km inland from the northern coast of Spain, forming a westerly extension of the Cantabrian Mountains. It consists of three main areas, the Western, Central and Eastern Massifs.
The village of Tresviso is in the Cantabrian part of the Eastern Massif (or Andara) and UK interest in the area started in the mid-1970’s with Lancaster University Speleological Society (LUSS). In the early years exploration was mounted from the village, and exploration was centred on the resurgence cave Cueva del Nacimiento (Cueva del Agua) located at the foot of the mountain range.
LUSS pushed Cueva del Nacimiento initially to 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 Nacimiento and hopefully create a record-breaking >1500m underground traverse.
They found several deep caves including the deepest found by a UK team at the time, Torca del Cueto de Los Senderos (Sima 56) at -1169m deep. However, a connection to Nacimiento remained elusive and UK interest started to wain and gradually Spanish clubs started to visit regularly, leading to the discovery of a deeper cave, Torca Jou Sin Tierre (CS-9) at -1203m deep.
UK cavers started returning to the area from 2009 onwards and made Nacimiento exploration the main focus, returning to the furthest reaches of the cave and exploring upwards, leading to further discoveries, slowly creeping up the mountain with the same goal of trying to connect to the deep caves and create a cave in the top 10 of the worlds’ deepest, the deepest in Spain and potentially one of a handful of deep through trips in the world.
Torca Brana Espina (originally just called C29) was first discovered in 1973, a Yorkshire like pothole descending to -110m and a sump. It’s located right next to the road that leads from the village of Sotres to Tresviso, conveniently close to a ‘carpark’ built for hikers in the mountains! More importantly it sits almost exactly in the middle between the resurgence and the potholes. Largely ignored by the more recent expeditions as it sits right on the border of permissions between Cantabria and Asturias. This change in 2022 when the permission boundaries were extended.
In 2023, the sump was free dived and found to be only 4m long, leading to more pitches, and it reached a respectable -500m depth with an awkward continuation in a well-developed rift series. In 2025, during the 50-year anniversary celebration of British exploration to Tresviso, the limit was passed unexpectedly to a major streamway, running west to east. East heads downstream in the direction of the Cueva del Nacimiento resurgence, just short of 2km away and with only 100m drop in elevation to the level of the main streamway in Nacimiento. Upstream, the cave splits into two major inlets, with one turning south and heading toward Sima 56 (1.7km away and 40m higher).
The passage, both upstream and downstream, was left with walking / swimming size leads heading off into the distance
..!
The discovery of this new streamway has changed the picture of exploration. Described by one of the original explorers, as “the most significant find since the 80’s”, this streamway could be the long-hypothesized trunk route between the high caves on the Andara plateau and the resurgence. There is a good chance that this can be extended both down the valley, to the main fault heading toward Nacimiento and up the mountain towards the very bottom of Sima 56.
Torca Brana Espina will be the main objective in 2026 and will see a lot of caver traffic through the expedition. It has now been left permanently rigged for 3 years and the same number of winters so urgently needs re-rigging for safety reasons and the expected increase in trips. The entrance series (the first -500m depth) starts off nicely and gets more tortuous, before hitting the stream. The streamway is cold and wet, so a nicer and more rescue friendly entrance would be ideal. On the surface there are a few other ‘old’ caves that are being revisited with a hope to connect through to the new system.
Permission has also been granted to conduct further dye traces. Initially, this will by tracing the water from Torca Brana Espina to Cueva del Nacimiento. It is assumed the water passes this way via an unknown larger continuation.
The discovery of the Brana Espina streamway means a slight change of objectives in Nacimiento will be undertaken. A number of high level fossil routes have not been explored since the 1970's, these are worthy of revisit as they are roughly at the same elevation as the 'roof' of the Brana Espina streamway and could yet provide a bypass to the main Nacimiento terminal sump, which is over 100m below the same streamway level.
The Expedition
The expedition runs from 4th September 2026 to 22nd September 2026 and includes 30 cavers from 9 different clubs, in
cluding 8 under 25’s. A successful rope sponsorship award from ukcaving would go straight to the rigging of Brana Espina which is going to take up most of our rope requirements this year. Updates will be posted here and on the website blog.
Useful links
More can be found on the Tresviso Caves Project here as well as an active blog which will also be used to give coverage to UKCaving for assisting with the expedition.
Website: https://tresvisocaves.info/
Instagram: https://www.instagram.com/tresvisocaves/
Previous reports: https://tresvisocaves.info/publications-tresviso-caves-project/
2023 entry
2019 entry
2018 entry
2017 entry
Overview & brief history:
The Picos de Europa is a range of mountains 20km inland from the northern coast of Spain, forming a westerly extension of the Cantabrian Mountains. It consists of three main areas, the Western, Central and Eastern Massifs.
The village of Tresviso is in the Cantabrian part of the Eastern Massif (or Andara) and UK interest in the area started in the mid-1970’s with Lancaster University Speleological Society (LUSS). In the early years exploration was mounted from the village, and exploration was centred on the resurgence cave Cueva del Nacimiento (Cueva del Agua) located at the foot of the mountain range.
LUSS pushed Cueva del Nacimiento initially to 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 Nacimiento and hopefully create a record-breaking >1500m underground traverse.
They found several deep caves including the deepest found by a UK team at the time, Torca del Cueto de Los Senderos (Sima 56) at -1169m deep. However, a connection to Nacimiento remained elusive and UK interest started to wain and gradually Spanish clubs started to visit regularly, leading to the discovery of a deeper cave, Torca Jou Sin Tierre (CS-9) at -1203m deep.
UK cavers started returning to the area from 2009 onwards and made Nacimiento exploration the main focus, returning to the furthest reaches of the cave and exploring upwards, leading to further discoveries, slowly creeping up the mountain with the same goal of trying to connect to the deep caves and create a cave in the top 10 of the worlds’ deepest, the deepest in Spain and potentially one of a handful of deep through trips in the world.
The 2026 objectiveTorca Brana Espina (originally just called C29) was first discovered in 1973, a Yorkshire like pothole descending to -110m and a sump. It’s located right next to the road that leads from the village of Sotres to Tresviso, conveniently close to a ‘carpark’ built for hikers in the mountains! More importantly it sits almost exactly in the middle between the resurgence and the potholes. Largely ignored by the more recent expeditions as it sits right on the border of permissions between Cantabria and Asturias. This change in 2022 when the permission boundaries were extended.
In 2023, the sump was free dived and found to be only 4m long, leading to more pitches, and it reached a respectable -500m depth with an awkward continuation in a well-developed rift series. In 2025, during the 50-year anniversary celebration of British exploration to Tresviso, the limit was passed unexpectedly to a major streamway, running west to east. East heads downstream in the direction of the Cueva del Nacimiento resurgence, just short of 2km away and with only 100m drop in elevation to the level of the main streamway in Nacimiento. Upstream, the cave splits into two major inlets, with one turning south and heading toward Sima 56 (1.7km away and 40m higher).
The passage, both upstream and downstream, was left with walking / swimming size leads heading off into the distance
The discovery of this new streamway has changed the picture of exploration. Described by one of the original explorers, as “the most significant find since the 80’s”, this streamway could be the long-hypothesized trunk route between the high caves on the Andara plateau and the resurgence. There is a good chance that this can be extended both down the valley, to the main fault heading toward Nacimiento and up the mountain towards the very bottom of Sima 56.
Torca Brana Espina will be the main objective in 2026 and will see a lot of caver traffic through the expedition. It has now been left permanently rigged for 3 years and the same number of winters so urgently needs re-rigging for safety reasons and the expected increase in trips. The entrance series (the first -500m depth) starts off nicely and gets more tortuous, before hitting the stream. The streamway is cold and wet, so a nicer and more rescue friendly entrance would be ideal. On the surface there are a few other ‘old’ caves that are being revisited with a hope to connect through to the new system.
Permission has also been granted to conduct further dye traces. Initially, this will by tracing the water from Torca Brana Espina to Cueva del Nacimiento. It is assumed the water passes this way via an unknown larger continuation.
The discovery of the Brana Espina streamway means a slight change of objectives in Nacimiento will be undertaken. A number of high level fossil routes have not been explored since the 1970's, these are worthy of revisit as they are roughly at the same elevation as the 'roof' of the Brana Espina streamway and could yet provide a bypass to the main Nacimiento terminal sump, which is over 100m below the same streamway level.
The Expedition
The expedition runs from 4th September 2026 to 22nd September 2026 and includes 30 cavers from 9 different clubs, in
Useful links
More can be found on the Tresviso Caves Project here as well as an active blog which will also be used to give coverage to UKCaving for assisting with the expedition.
Website: https://tresvisocaves.info/
Instagram: https://www.instagram.com/tresvisocaves/
Previous reports: https://tresvisocaves.info/publications-tresviso-caves-project/
2023 entry
2019 entry
2018 entry
2017 entry
