Lago Ercina

Speleogroup  title


Site list (GPS fixes) Walks (GPS tracks)  Video clips Panoramas

Coordinates used

Electronic projects:

 Bat detector
 Lamp tests
 µ-controlled lamp
 SEPIC-based lamp
 ISP isolators
 Making SMT boards

Expedition logs:

  Spain 1973, 1974,
  1975, 1976, 1977,
  1979, 1982, 1983,
  1985, 1986, 1987,
  1988, 1989, 2000,
  2001, 2002, 2003,
  2004, 2005, 2006,
  2007, 2008, 2009,
  2010, 2011, 2012,
  2013, 2014, 2015,
  2016, 2017, 2018,
  2019, 2020, 2021,
  2022, 2023
  New England


 The Battle of
 El Mazuco

Speleogroup is a caving club, formed in 1969.  On this site are details of some of our projects, summaries or transcriptions of our caving expedition logs, and a translation of El Mazuco (La defensa imposible).

Click here for the latest (2023) expedition log.
Sadly, this was Bill Collis’ last trip to Spain.

Electronic projects

Project Description
Lamp tests Live (in-cave) lamp tests of Luxeon Star LED lamps
ATtiny-A Luxeon Star LED caving lamp based on the Atmel ATtiny15L AVR microcontroller
LT1512-A Luxeon Star LED caving lamp based on the LT1512 SEPIC (buck/boost) battery charger IC
ISPisolaters ISP Isolators for Atmel AVR microcontrollers
SMT boards How to make SMT boards at home (pictorial)
Bat detector Building a frequency/amplitude-recovering bat detector


Members of Speleogroup have participated in the following expeditions to Northern Spain.  See also our list of speleological sites,  a selection of our walk tracks,  panoramas,  and video clips,  and our notes on the mapping coordinate systems used.
Year Primary destination(s) Notes/with
1973, August & September La Hermida Gorge
Illustrated BUSS & OUCC »
1974–1975, New Year Rales and Llanes Illustrated
1975, July & August Rales system, Pozo del Infierno, Los Lagos, Forcau, La Hermida Illustrated SCAL, Montpellier
1976, July Vega El Forcau
(Forcau ’76)
Illustrated OUCC (Proceedings 8 », or text version »)
1977, April Reconnaissance, Garma Ciega and Ribadesella Illustrated Quad-C, CCCC
1977, July Garma Ciega Illustrated OUCC, MUSS, PCG
1979, July Los Lagos, Toyu, Ramales Illustrated OUCC
1982, July La Franca, Suarías, Latarma & Toyu survey Illustrated IBMCC
1983, July & August La Franca & Llanes », El Cuevón de Pruneda (Purón) Illustrated
1985, August La Franca, Pruneda, Los Lagos, Fuentica, La Hermida & Bejes Illustrated OUCC, Rales cavers
1986, August Pruneda, Pozo del Infierno, Cueva Negra, Rafa’s group, Toyu Illustrated Rafa & ‘The Wild 13’
1987, July Rales, El Mazuco, Tinganón Rafa & Spanish group
1988, August via France; Cabañuca, La Boriza, Rioja Illustrated
1989, July Llanes area, Mestas, Socueva, La Borbolla Angel; Speleogroup’s 20th Anniversary
2000, July Fuente Dé, Tinganón, Fuentica Illustrated
2001, July Cubilla, El Mazuco, Orandi, Viango, Pozo del Infierno Illustrated
2002, June El Mazuco, Pruneda, hikes, General Strike, Cabañuca Illustrated
2003, July Andinas, Bulnes, Trumbio, Viango, Cueva Negra, high Picos Illustrated
2004, June Bulnes, Cueva Bolado, Green Sink Illustrated
2005, July & August Rales, Peña Blanca, Espinosa, Ramales, Durango Illustrated Rales cavers
2006, June & July Gesaltza, Viango, Forcau, Devoyu, Ramales, Balzola Illustrated
2007, June High Picos, Devoyu, Caín, Rales, Sotres Illustrated
2008, June & July Tinganón, Bulnes, Suarías, high Sierra towards Turbina Illustrated
2009, June & July Tayada, Peruyal, Cofría, Valmayor, Negra Illustrated Speleogroup’s 40th Anniversary
2010, July Cudillero, Bufones×2, Tresviso, Río Purón, Cofría, Cueva del Arco Illustrated
2011, May Áliva, Cofría, Avín, Tenis, Dobros, Forcau, Llonín, Caín Illustrated
2012, June Potes, Nansa & Saja valleys, Gulpiyuri, Andara mines. Illustrated
2013, July Potes, Cangas, Pruneda, etc. Illustrated 40th anniversary of first caving in Spain
2014, June & July Llanes, Orandi, Pruneda, Potes, Urdón canal, San Vicente, Cobijón Illustrated
2015, August San Vicente, Potes, Llanes, Cabañuca, Fuentica Illustrated
2016, June Cicera, Trumbio, Cobijeru, Vega de Hibeo, Toyu Illustrated
2017, June Cueva del Toyu, first drone explorations, Cobijón, Cheese Crawl (a cheese a day) Illustrated
2018, May Los Tocinos, Cubilla, La Borbolla, Cueva del Toyu, Tinganón Illustrated
2019, March Villa, Tebrandi, Boriza & Pozo de Fresno, Potes, Tresviso, Bolado Illustrated
Speleogroup’s 50th Anniversary
2019, June Mazacuíos, Bufones de Santiuste, Boriza, Cobijeru, Rejo/Cofría, Tayada, Tenis
2020, March Ribera del Duero, Oviedo, Llanes, Pierre Saint Martin Illustrated Coronavirus stopped play.
2021, September Bolado, Cobijeru, arches, drone + 360°, Matienzo Illustrated Masks! 
2022, March Bufones, Llamigo, Pruneda resurgence, Cobijeru×2 Illustrated Fewer masks, etc.
2022, June Cobijeru×3, Bolado, Los Tojos, tamarisks, bufones, Caldueñin Illustrated No masks, except on aeroplanes.  Hot! 
2022, October Cuevas del Mar, Tresviso, Trumbio walk, Cobijeru, El Arco drone Illustrated Pleasant weather.
2023, March & April Cueva del Cuélebre, Los Lagos, Cueva Bolado UV-C, Tito Bustillo, Museo de la Emigración Illustrated No masks! 50th anniversary of first caving in Spain.
Illustrated Illustrated page; all photographs are contemporary with the log in which they appear.
✗   Log is a summary; transcription not yet available.  All other logs are complete transcriptions of original handwritten (or typewritten) logs.  All original text was written in the field by Bill Collis and/or Mike Cowlishaw, except where noted.

Speleogroup members have also participated in the following explorations:
Year Primary destination with
1969– UK BEC », BUSS, IBMCC, MCS », OUCC », SWCC »
1974, summer Co. Fermanagh BUSS
1978/9, winter Mexico – City, Cuetzalan, Chiapas, Palenque, Popocatépetl, etc. Illustrated IBMCC & North-American cavers
1980/1 USA, New England Yorktown High »
1982, April Co. Clare IBMCC
1983, April Co. Clare IBMCC, KCC
1986– Italy  
2003, October Hawai’i Big Island » Lava tube caves  

Other projects

Project Description
The Battle of El Mazuco A translation of El Mazuco (La defensa imposible) by Juan Antonio de Blas, in La guerra civil en Asturias, Tomo 2, 1986.
MapGazer » MapGazer is a new application for viewing offline maps (maps stored on disk) on a Windows personal computer (PC, laptop, or tablet, running Windows 7 or later). It is especially useful when the device in use has an unreliable (or no) internet connection (as is often the case ‘in the field’).
PanGazer » PanGazer is a new application for viewing images and panoramas, including 360° spherical and hemispherical panoramas as captured by drones, on a Windows personal computer (PC, laptop, or tablet, running Windows 7 or later). It is especially useful for setting and using geographical information (e.g., bearing of images) and extracting ‘stills’ from spherical panoramas.

Expeditions to the Picos de Europa and elsewhere since 1973.
Please e-mail Mike Cowlishaw ( if you have any corrections, suggestions, etc.   See also the SpeleoTrove speleology section ».
The pages and data here are for non-commercial use only.   All content © Speleogroup 1973, 2024, except where marked otherwise.  All rights reserved.  Here is our privacy policy.

This page was last edited on 2024-01-03 by mfc.