Tresviso 2022 Summary

The Tresviso 2022 expedition just returned from Spain a few weeks back. A very busy and successful trip which left little time for updating the blog (again). The following is a summary and the full report will follow shortly.

Overview:
The 2022 expedition was to continue with ongoing exploration in Andara (Eastern Massif) of the Picos de
Europa, Northern Spain. A team of 26 cavers were based in either Tresviso or camping on the Andara plateau to tackle the main caves.

Cueva del Nacimiento is a large resurgence cave in the gorge below Tresviso. Originally explored in the 1970’s and 80’s it was pushed to a terminal chamber ‘Death Race 2000‘, ~400m above the entrance. 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 de la Marniosa, a smaller inlet cave to Nacimiento. A new entrance in 2018 has enabled a mini through trip to be completed and continued exploration reveals new sections of cave each year. Dye traced to Nacimiento in 2018

Sistema Sara. A deep (-590m) pothole on the plateau, including a >200m pitch near the start. Not visited by a UK team since 1996 and only an aborted Spanish trip in 2015 has been back.

Objectives:
The main objectives of the 2022 expedition were:

• Cueva del Nacimiento – Exploration at the far end ends in a draughting hole, that requires digging. This is the highest and furthest point in the cave and most likely the ongoing continuation of the cave deepr into the mountain
• Cueva de la Marniosa – Upstream Marniosa is >2km of windy, rift like streamway, that in 2018 was connected to surface pots coming in at the head of the main valley. Although this is in the opposite direction to a connection with Nacimiento, the passage here may be key to connecting to the deep potholes coming in from the Andara plateau. A large chamber (Alien Weaponry) was found in 2019 part way along the streamway, and some large avens enter this chamber.
• Sistema Sara – an ambitious plan to dive the final sump in Sara, by all reports the largest streamway of any of the alpine pots in Andara and a high contender for the main drain of the region. The only stumbling block being that it has not been visited in nearly 30 years.

Alongside the exploration of new passage, one of the overarching aims of the Tresviso Caves Project is to collate and document the area, providing an online database for all the caves in the region. To date 79kms of cave across 1095 sites have been described, logged, and made publicly available along with relevant surveys, descriptions and possible leads.

Results:
Cueva del Nacimiento – Mendip Mission
In 2021 the way on was stopped at a tiny calcited crack. Despite being told by numerous people that ‘it was a waste of time’, a team of 3 spent 4 hours hammering away at the constriction and eventually passed it to around 60m of new cave and a climb. A second group passed the climb and found over >200m of new cave and multiple ways on. This is an exciting discovery, and the new passage lies on an obvious fault. The 2023 expedition will concentrate heavily on this new lead.

Cueva del Nacimiento – Road to Certain Death
A last minute addition to objectives. The Certain Death sump has remained un-dived since 1996, but after 2 days of rigging and kit hauling a diver entered the sump and quickly found the way on at the limit of previous exploration. Another 200m of sumped passage (making 400m total) surfaced in dry passage and a further sump. The second sump was passed after 40m to a dry chamber and several possibilities for future exploration.

Cueva del la Marniosa – Other
Approx. 1km of cave was resurveyed (500m of it being new). Frustrating a lot of question marks from the 70’s surveyed proved to have been visited and contained surveying ‘stations’ (but no drawing up anywhere!). However, a number of new leads have been identified, include some high level climbs approaching the first sump. These will be visited in 2023 as they may provide a route past the sump for dry cavers to aid divers at the far end of Marniosa.
The Alien Weaponry avens were climbed but remain ongoing.

Cueva del Rio Chico – Sump
Another last minute addition to objectives. Chico sump 2 was also dived in the first few days of the expedition. Unfortunately, it continued at depth (-80m) and continues in similar fashion for over 80m
Sistema Sara Sara was re-rigged over the first week of the expedition and the sump dived soon after. It continued for around 30m at a depth of -22m. Unfortunately, it proved to be heavily silted and zero vis but it does push the cave to over -600m deep. The cave was then derigged with a few days spent looking at the area of Leper’s Lament, following discussions with 80’s cavers on big ‘cathedral sized’ voids to be explored. These did not amount to much more that alcoves and pitches dropping back into the known cave.

Summary:
In total over 1.5km of new cave was surveyed in 2022, a further 4km of existing cave was also resurveyed,
largely in Cueva del Nacimiento as the beginning of a new multi-year project to accurately resurvey the entire cave. It is worth noting that the ongoing resurveying of various caves in the area is proving extremely valuable in finding new (or forgotten) bits of cave. Rio Chico was resurveyed this year, and from the early 70’s has always been recorded at being around 600m long, following the resurvey it was found to be closer to 1km long and once the new sump survey added, almost 1.3km long and still contains a number of potential leads.

In Nacimiento the discovery of the main way on, Mendip Mission, was an added bonus towards the end of the expedition. A number of leads remain, and an obvious fault has been encountered, that will hopefully provide more success in 2023. Likewise, the successful passing of the Certain Death sump was also a major achievement. Although further exploration here is unlikely, at present, it highlights what can be achieved nowadays with modern equipment.

The diving of the Sistema Sara sump was also a huge achievement. A fairly formidable and daunting cave was re-rigged, and one dive of the sump was attempted. Despite it not being passed the effort to reach that point cannot be underestimated.

To quote a member of the expedition:

The rigging in the Heinous Shaft alone used ~280-300m of rope, ~50 bolts, 19 rebelays and 1 traverse to create a wonderful and unique journey through one of the more terrifying shafts in the Picos de Europa.