Eastern Massif, Picos de Europa, Northern Spain

In 2023 the Tresviso Caves Project continued work in Cueva del Nacimiento, Cueva de la Marniosa and ongoing work on the Andara mountain range, specifically T169 Torca del Picu Boro (Flowerpot)

G.E. Flash & Tracalet continued work in Samelar, revisiting numerous caves.

Tresviso 2023 (TCP)


The 2023 expedition was to continue with ongoing exploration in Andara (Eastern Massif) of the Picos de Europa, Northern Spain.


The main objectives of the 2023 expedition were:

Cueva del Nacimiento 

  • Mendip Mission – at the furthest point in the cave, there are multiple leads, these will be explored. 
  • Far Upstream Sump – an attempt on the sump will be made in 2024, this year diving equipment will be carried in and stored in the cave. 
  • Resurveying project – commenced in 2022, will be continued.

Cueva de la Marniosa 

  • Beyond Sump 2 – an undescended 6m pitch will be descended by small team of divers. 
  • Sump 1 Bypass – investigation of high level leads in the streamway, looking for a bypass to the first sump. 
  • Alien Weaponry – 35m aven partly climbed in 2022 will be completed. 
  • Derigging – several aven climbs, now finished, will be de-rigged. 
  • Surveying – new modern survey required.  This will include the unsurveyed discoveries from 2018 and as far as possible into the known cave. 

T169 Torca del Picu Boru (Flowerpot) 

  • Unexplored leads – a number of potential leads will be investigated. 

This year, permission has been extended into the Asturias region, specifically the area around Sotres and La Caballar.  This will allow exploration of some of the caves that potentially sit between the deep caves of Andara and the resurgences in the Urdon Gorge3

Cueva C29 

  • Terminal Sump – sump at -120m is 1975 limit of exploration.  Investigate and dive the sump. 


The 2023 expedition has continued to build on the successes of previous trips discovering over 2.5km of new cave and several new leads. Over 3km of existing cave was also resurveyed to improve accuracy of old data and provide a better picture of the interconnected systems. 

Cueva del Nacimiento – Barbenheimer 

In Nacimiento exploration continues to push the cave further into the mountain, but now passage is increasingly heading downwards, although this is away from the surface, it is promising as the cave follows a similar profile throughout the cave, steep ramps up, followed by drop in height to next the next ramp ups. 

In addition, dive bottles have been carried into Nacimiento, ready for a dive of the upstream sump in 2024. 

Cueva del la Marniosa – Beyond Sump 2 

The undescended pitch beyond Sump 2, discovered in 2018, was finally dropped and a short section of passage unfortunately leads to a third sump.  Iin 2024 the search for possible bypasses to the sumps will continue.  

Cueva C29 – Torca de Brana Espina 

Cueva C29 was a major success on the trip, pushed to just short of -500m deep and appears to lie on the fault directly between the higher potholes and the resurgence caves.  The cave continues with unexplored passage and will be visited again in 2024. 

Cueva de Concha Vies 

The cave has been rigged to the previous limit of Spanish exploration (1996) and will be progresses further in 2024. 

T169 Torca Picu Boru 

The Bill Series was re-rigged, surveyed and fully explored.  The main route, via Ben Series was also re-rigged and surveyed down to the -277m, with some new leads identified. 


Phil WalkerBradford Pothole ClubUK2023Tresviso 2023
Dan WorkmanBradford Pothole ClubUK2023Tresviso 2023
Sam DeeleyBradford Pothole ClubUK2023Tresviso 2023
Rob MiddletonBradford Pothole ClubUK2023Tresviso 2023
Josh BratchleyBradford Pothole ClubUK2023Tresviso 2023
Dave PowleslandCardiff Hill DiversUK2023Tresviso 2023
Ian HolmesChelsea Spelaeological SocietyUK2023Tresviso 2023
Tom LiaCardiff Hill DiversUK2023Tresviso 2023
Toby DrydenSouth Wales Caving ClubUK2023Tresviso 2023
Julian CarterSouth Wales Caving ClubUK2023Tresviso 2023
Si LowisSouth Wales Caving ClubUK2023Tresviso 2023
Lisa BooreGagendor Cave ClubUK2023Tresviso 2023
Sam HillShepton Mallet Caving ClubUK2023Tresviso 2023
Callum SimmondsShepton Mallet Caving ClubUK2023Tresviso 2023
Wendy AtkinsonYorkshire Speleological SocietyUK2023Tresviso 2023
Howard JonesSociety of Lancaster Undergraduate SpeleologistsUK2023Tresviso 2023
Alastair GottTechnical Speleological GroupUK2023Tresviso 2023
Bob ClaySouth Bristol Speleological SocietyUK2023Tresviso 2023
Ben ThompsonSheffield University Speleological SocietyUK2023Tresviso 2023
Ben AlstonSheffield University Speleological SocietyUK2023Tresviso 2023
Michael HollidaySheffield University Speleological SocietyUK2023Tresviso 2023
Glen SankeySheffield University Speleological SocietyUK2023Tresviso 2023
Alex FirthSheffield University Speleological SocietyUK2023Tresviso 2023
Joe WalkerSheffield University Speleological SocietyUK2023Tresviso 2023
Illia LytvyniukSheffield University Speleological SocietyUK2023Tresviso 2023
Pat ToughSheffield University Speleological SocietyUK2023Tresviso 2023
Tomas BattenSheffield University Speleological SocietyUK2023Tresviso 2023
Andie RedrupSheffield University Speleological SocietyUK2023Tresviso 2023
Tomass BaltmanissSheffield University Speleological SocietyUK2023Tresviso 2023
Nitta ThonskulprasertSheffield University Speleological SocietyUK2023Tresviso 2023
Max KenworthySheffield University Speleological SocietyUK2023Tresviso 2023
Leo BradleySheffield University Speleological SocietyUK2023Tresviso 2023
Arwel RobertsSouth Bristol Speleological SocietyUK2023Tresviso 2023
Derek CousinsSociety of Lancaster Undergraduate SpeleologistsUK2023Tresviso 2023
Alex HannamShepton Mallet Caving ClubUK2023Tresviso 2023

Documents & Links


Tresviso 2023 (ES) 18 MB 8 downloads

Spanish Translation ...

Tresviso 2023 25 MB 20 downloads


    Bejes 2023 (G.E.Flash)


    Continue with the exploration and topography of cavities SN-21 and SN-6, in the North Samelar area and cataloguing of the cavities with the presence of snow or ice existing in the exploration area.

    Juan A. Martin OteroGE FlashES2023Bejes 2023
    Jorge Mateos de la FuenteGE FlashES2023Bejes 2023
    Belen Hernandez FernandezGE FlashES2023Bejes 2023
    José Luis Izquierdo MorenoGE FlashES2023Bejes 2023
    Sergio Rodríguez TolobaGE FlashES2023Bejes 2023
    Javier Gutierrez NevadoGE FlashES2023Bejes 2023
    Carlos Pérez RelTracaletES2023Bejes 2023
    Marc Verdú CazañaTracaletES2023Bejes 2023
    Vicente Martínez MontalarTracaletES2023Bejes 2023
    Maria Jesus Tevar OviedoTracaletES2023Bejes 2023

    Documents & Links


    Bejes 2023 5 MB 1 downloads


      Portudera 2023 (Club d’Espeleologia l’Avern)


      Since 2016 Club d’Espeleologia l’Avern de Ontinyent (Valencia) have been exploring the area of Portudera in the Eastern Massif. The project aims to catalogue and explore the caves in this area


      Exploration of Torca Jocejerru


      Vicent SanchezClub d'Espeleologia l'Avern OntinyentES2023Portudera 2023
      Rebeca DiazClub d'Espeleologia l'Avern OntinyentES2023Portudera 2023

      Documents & Links


      Portudera 2023 (en) 5 MB 7 downloads

      English translation of 2023 report ...

      Memorias Portudera 2023 3.4 MB 18 downloads