Tresviso 2016


The 2016 expedition was to continue with ongoing exploration in the Cueva del Nacimiento cave in the Urdon Gorge (Tresviso, Cantabria). Expeditions in the previous years have been slowly extending the cave up through the mountain range, with the intention of trying to connect the cave with the known deeper pot holes in the Andara region. A number of the caves higher on the mountain (Sima 56, Sara) have previous been dye tested and the water is known to resurge in Cueva del Nacimiento.


Cueva del Nacimiento – Die Hard – Jurassic World. The 2015 expedition successfully reached the highest known point in the cave, the Jurassic World, with a number of leads to progress in 2016.

Cueva del Nacimiento – Teeth of Satan – Wet Aven. The 2014 expedition partly climbed a promising aven, part way up the Teeth of Satan ramps. The aven requires completion in 2016.

Cueva del Nacimiento – Grand Circle. The Grand Circle is an area of passage around the main stream way at the far end of the cave. Although explored fairly rigorously in the late 70’s this was before the advent of more powerful lights and better equipment. Given the profile of the cave, exploration in this area would be worthwhile to try and find a middle dry phreatic level above the Far Upstream Sump.

Cueto de Entre Cuetos. The 2009 trip pushed this cave down to a small stream way, this still requires exploration and the cave is in a good central location for dropping into the top of Nacimiento.

Al2. Discovered in 2005. A drafting shaft not yet bottomed. Jurassic World in Nacimiento appears to be heading directly towards this site.

Pozo Del Castillo. Reinvestigate the possibility of resuming exploration of the Castillo system, currently at -293 m.


Cueva del Nacimiento – Die Hard – Jurassic World. The Sandy dig was excavated for 4 hours, but sand soon gave way to large calcite blocks. Only long term excavation would potentially pass this limit. Exploration abandoned. At the start of the Jurassic World, is the Dinosaur Aven. This aven was climbed in 2016 over 3 trips. The height reached was 55m before the aven started to close down into a small rift. Just off the Death Race 2000 chamber a small rift was followed, Joes Crack, this currently extends for 20m down a draughting rift. Although the passage heads back under the cave, it may provide a lot of dry passage if explored further. Another aven near the start of the Die Hard passage was discovered. I’m Not Into Yoga was another 60m aven and provided another 120m of cave passage.

Cueva del Nacimiento – Teeth of Satan – Wet Aven. The Wet Aven was climbed over 3 trips. The main aven is 44m high before a cross passage is reached, the cave then continues up 3 small pitches. The passage here has the characteristics of a traditional pot hole entering the cave. However, the top of the last pitch is a small calcite hole that will require hammering.

Cueva del Nacimiento – Grand Circle. The Grand Circle was revisited but no ways on could be found at the higher level. The lower level was previously explored in 2012. There appears to be no dry levels above the upstream sump and only continuing climbs in Death Race would appear to hold the route into the mountain.

Cueto de Entre Cuetos. The cave was rigged over 2 days and a number of ‘smaller’ cavers attempted to pass the terminal restriction. The final passage continues to get smaller with no way to turn around. Exploration was abandoned.

Al2. It was not possible to relocate this cave. The cave lies in a heavily wooded area of the Sierra del a Corta and was originally discovered in Winter, when the terrain was considerably different and the cave easier to find.

Pozo Del Castillo. Pozo Castillo was located and re-explored. The blockage that has prevented progress since 1987 is still in place and consists of a number of large boulders held up by a snow plug. Without significant shoring work the obstacle appears to be impassable. However, the neighbouring Pozo Natacha cave, currently finishes at a similar depth to Castillo and survey work
would seem to suggest that they (and others in the area) are feeders into a main system. Natacha was rigged to the final pitch and will be revisited in 2017 to confirm this theory and hopefully extend the cave.

Other exploration. Cueva del Marniosa was revisited. An unsurveyed inlet near the upstream end of the cave was explored for 140m. Cueva del Valledal was revisited. This was an unsurveyed cheese cave, close to Tresviso. 160m explored and surveyed.


In total nearly 1km of cave was surveyed in 2016. Exploration of Nacimiento continues to provide challenging due to the remote nature of the leads at the end of the cave. Trips to the far end require 4-5 nights of camping, in order to adequately provide time to push and explore the leads. Although there are a number of leads in the near entrance series of Nacimiento, and real gains toward the deep systems on Andara would need to be made in the Death Race – Die Hard – Jurassic World area.

Text: Phil Walker
Photos: Russell Brooks & Jason Gotel

Download: Summary Expedition Report


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