Updated 26th October 2016; 24th September 2018; 21st September 2022

   A well-known cave in the area that has been explored and surveyed by the Grupo Espeleológico de Santander del C.A. Tajahierro. Their survey is published in Exploraciones en Solorzano (Santander) in Los Sótanos de la Tierra, No. 5, 1980, Santander (ref. 1980a).
  Nowadays, the entrance to this cave is through a locked grille (but broken in August 2022) at the Medical Centre, from where the key can be obtained. The cave floods in wet weather.
   Beyond the door there is lots of broken glass and the passage is then varied going from walking size to flat out. A side passage on the left (on the way in) has been opened up to easy going, keyhole-shaped passage trending down to a pool of water with a blind climb to a rift above. The main passage goes for about 200m to a sump.
   The sump was dived in August 2016 when Colin Hayward - in water conditions about a metre lower than normal - passed through a duck then into the sump to reach a chamber, having laid 30m of line. The chamber is roughly 5m each side with a mud bank down the middle. Around the outside, a dry water course was observed leading from a low passage in the southwest corner. A questionable boulder bridges the passage and this may need breaking up before it is safe to proceed.
   On the same day, the climb down near the entrance, previously sumped, was found to be a watery rift along the same line as the streamway with routes going off in both directions. Neither way was explored.

   In July 2018, the sump was found to be choked with gravel, probably due to heavy rains earlier in the year.

  In very dry weather (a drought), a 6-person team passed through the sump sections with air space. The following account of the 91m of passages surveyed is slightly amended from a logbook entry by Andrew Northall (3/8/22):
   The entrance was found unlocked (no key required) and the broken glass in the entrance did not present much trouble – it was sparse and easily possible to crawl around safely. The sump was located within around 15 minutes of caving and it was a sharp descent down a gravel bank into a dry crawl where the water was immediately met. There was airspace all the way through the sump and it was easily passed as a 0.5m duck, followed by a large airbell, followed by another 0.5m duck to arrive in the chamber described by Colin Hayward. (2016).
    The questionable boulder was passed by crawling under it and a mix of crawling and stooping shortly arrived at a boulder choke in a large chamber. The boulder choke was easily navigated to arrive in a dry, walking passage streamway, with all walls and ceilings coated in a thick layer of mud. Several chimneys were observed to rise up to higher level passage in this area, and one was climbed (although not surveyed) to arrive at the base of a clean washed aven of approximately 6 - 8 metres in height. Further passage was seen (not surveyed) to branch off from the top of this aven however it would require bolting and capping to access. The maximum surface elevation in this area is around 100 metres and the survey shows that these upward chimney passages and avens must come very close to the surface, potentially limiting the development of a useful high level system.
    Abundant pieces of surface debris (trash, leaves) were observed in the cave passages.
    Travelling further along the extended streamway, a junction chamber was reached with two ways on. The first, a flat out squeeze in the right hand wall (likely sumped when the streamway is flowing), required digging to access and was quickly followed by another flat out squeeze which also required digging. A small chamber was reached with a tight way on up a mud slope (needs digging in mud), or a too tight stream passage (needs capping). We turned around here and no noticeable draught was felt.
    Back at the junction chamber, the other way on was a tight stream passage which was blocked by a long, thin boulder. This would require either hammering or capping but once removed, the passage is large enough (at least initially) to access.

Link to entry in the Cave Diving Sump Index.

Reference: anon., 1980a; anon., 2014b (Easter logbook); anon., 2016c (summer logbook); anon., 2018c (summer logbook); anon., 2022c (summer logbook)
Entrance pictures : Easter 2014
Underground pictures : Easter 2014 : August 2016
Video : dive August 2016 (YouTube)
Detailed survey : from anon., 1980a : pdf April 2014 (revised grid ref 2018) : sump area sketches, August 2016 : pdf August 2022
Line Survey :
On area survey :
Survex file : 2022