Updated 15th May, 16th September, 31st October 2020; 5th March, 21st May 2021; May, 4th October 2022; 23rd May 2023

Joint exploration with La Cambera was hoped for at Easter 2022, but the club was elsewhere.

   First documented as site X013. The working name is shown above until a local name is obtained.
   A large entrance to a resurgence cave. The dammed water outlet reaches a canal with deep, cold water after 30m. A tourist trip in the summer, 2019 reached a draughting rift. The site was dry at the entrance when visited in the summer, 2020 but produces copious quantities of water in flood. In April 2022, the water levels seemed to be much higher than the first MCP visit as a bouldery climb at the end was not found and was presumed to be under water. There was no trace of the draught reported earlier.
   La Cambera reached the canal in January 2021 but didn't continue. Joint explorations should be arranged.
   The entrance position appears to be pin-pointed with mapas.cantabria.es LIDAR information at 447757, 4804104. A GPS reading 10m to the west, in the entrance gorge, was 447744, 4804104. A surface survey is required, possibly up to a field boundary next to the road above.

   The water in the cave is held back by a low dam to the side of the cave entrance. This forms the intake for the water for the cattle troughs by the car park.
   The boulders in the entrance chamber can be seen to go up at least 8m very close to the road above. Almost immediately, the very cold water forms a deep narrow canal which is fairly straight but short arses need to swim. At one point, a constriction above water is best tackled as a duck under. About 10m beyond the narrow point, short passages on the north side (true right) lead to a cross joint about 1.5m above the sump proper. This is a roomy rift entered by ducking under the wall about 3 or 4m beyond the aerial passages. (Terry Whitaker logbook 17/4/2022)

   On a visit in wet weather (17/4/22) , there was no draught, water levels were up, and the rift at the end was not seen. An exploratory dive by Jim Lister reached a large underwater passage with a cobble floor. This was a major objective for the summer 2022 and the cave was extended with 8 sumps documented. Note that the survey contains "best guess" sections through murky sumps, and there are issues with .top files not providing full passage detail.

   The following description is based on logbook entries by Jim Lister and Mark Smith, 16 - 19th August 2022.

   From the back of the entrance chamber, deep water leads to sump 1. The route through has been lined through the deep water (?). The sump had obviously seen better days. Fertilizer and bits of animal manure seemed to be floating in the sump. The sump descended for 6 metres and approx 35 metres before surfacing in a chamber.
   Murky sump 2 is met after approx 10 metres and is about 20m in length. After approx 70m, sump 3 is reached, this time with crystal clear, blue water. The underwater passageway goes steeply down into a nice canyon and easy dive, surfacing after approximately 45m.
    Streamway was followed for a while before reaching another sump pool (sump 4 later dived by JL - see below) and a drafting ascending ramp to the left is followed. This continues through a few boulder filled chambers, one with a way on in the roof. The sharp shell encrusted rift passageway continues for a while to a traverse over a 5m drop (bottom checked), with a passageway leading to the right which entered a series of chambers.
    Down led to both an upstream and downstream sump (sump 5 and sump 6 both not dived). A climb above was enters another boulder choke with no clear way on.
   A draughting route to the north can be followed for approx 70m to a 5m pitch down to a sloping slab. A 2m climb down enters a watery chamber with a sump downstream (sump 7 ? not marked on survey) and a large chamber with unexplored roof. Upstream is a regular stream passage. Two side passages to the left would destroy wetsuits. The second one has a potential way on in the roof.
    The way on continues over fallen blocks in tight passageway before turning left and getting really tight. Passageway goes to a 3m climb which was ascended and the passageway beyond continued but small and full of sharp shells.
    Sump 4 remains completely clear while exploring beyond, indicating the explored passageway could be an inlet. When dived, approx 100m of passageway was followed but, again, it ended in a tight rift full of sea shells. There is a sump (not numbered) further back that cleared, so it looks like this is the main way on. Sump 4 extension was surveyed in April 2023 and will appear on the system survey below.