0373: Bosque, Cueva del
N Vega 30T 449238 4795981 (Datum: ETRS89. Accuracy code: G) Altitude 402m
Length 1022m (+30m unsurveyed upstream) Depth 204m
Area position

Updated 3rd October 2007; 24th October 2009; 16th September 2017; 4th, 8th January, 5th May, 30th June, 21st September 2018

   A stream sink in an obvious valley high up on the north side of La Vega, best approached from Las Calzadillas. The cave obviously floods but a quick visit after 2 days of heavy rain in December 2017 found the levels up a bit but still perfectly accessible.
   An aerial panorama of the area and video fly-over were made in 2018: details here.
   A climb down through the entrance choss lands on boulders and an obvious short climb down enters a fine 2m wide and 5m high stream passage which ends at an 8m pitch. An easy traverse over the top leads to a choked chamber and a slope down which drops to the chamber at the base of the pitch. The outlet is a short crawl to a loose chamber stretching across the passage above, and a further short crawl at floor level meets a collapse. A devious crawl up and to the left, over boulders, enters a tall, dank chamber about 10m long. The far end carries a minute streamway which chokes, while a hole down through the boulder heap at the near end regains the crawl which chokes after about 15m.
   The cave was descended again in 2007: an extension was made into the New Forest with a draughting crawl that needs digging. In August 2017, a bouldery hole in the floor of New Forest was opened up (YouTube video) and later, a c5m descent made into a 6 x 10m chamber with a dig in boulders. Slim Pickings was opened up in December 2017.
    Loose boulders were removed and a slot opened up which carried a noticeable draught. A 4m pitch drops into a slowly enlarging passage (Boxing Day Surprise) which soon enters a nice inlet chamber. Around the corner is the rather impressive view of a massive shaft where a rock whistles down to a booming crescendo after a freefall of around 5 or 6 seconds. This is Squirrel’s Pitch - 75m x 10m diameter drop in a beautiful, glistening, widening shaft. (A 4m traverse along a shale bed on the left of the shaft leads to a short drop over the lip to a Y hang rebelay. After 40m, another rebelay leads to a fine final free hanging descent to the base of the pitch.)
    The outlet is a tall, tortuous rift which is followed for about 15m to another pitch.
   Helmet Trapper (p10m), has a fairly tight squeeze to access but the actual take off is fine and soon opens out into a nice 3m diameter pot. This section of cave is in beautiful waterworn limestone and very reminiscent of Dales potholes. A comfortable descending streamway soon ends at a steep rift leading down to the take-off of the 50m deep Double Six Pitch, another stunning descent in a large, beautiful shaft with the stream falling at the far side.
    The base of the pitch is 15m by 8m with a flat boulder floor. The water sinks into the boulders and the only outlet is a small, flat out crawl directly opposite the landing. This short Roll Again crawl emerges in the Río Dado.
    Unfortunately, downstream, the route rapidly deteriorates into wet hands-and-knees crawling over pebbles and very quickly gets tedious. After around 200m the monotony is broken with a beautiful aven coated in slippery white calcite and moonmilk. Downstream from Slithery Turtle Aven (so named because of a peculiar shaped flake), a final 60m or so of grovelling ends at a sump. According to the area centre line survey, this sump is 200m away and 5m higher than an inlet that ends in boulders to the south of the Aquatic Junction in Torca del Regaton.
   Just before Slithery Turtle Aven an inlet on the right was pushed in April 2018. This is tight and gnarly and ends where it became too tight after about 116m.
   Upstream is a fine passage ending abruptly after about 100m at a sump. A large passage continues to the right of the sump but almost immediately ends at a very steeply ascending, draughting, boulder choke. This has been forced for 10 to 15m but to no avail. (This was checked again (with a smoke bomb) in April 2018 and the area of the choke declared a "no-hoper".
      The floor at the upstream sump was lowered in April 2018 along with removing boulders and hammering out the roof. The resultant duck was then passed into a 3m continuation to a further sump. This was later dived in a shallow 6m sump where 2 hanging flakes would need to be removed in order to make it a viable free-dive. Several deep pools were negotiated before entering the low upstream passage. After a brief duck the passage changed to hands-and-knees proportions then abruptly ended at a small, very loose collapse chamber. The way on looks very low and is blocked by several large boulders which would require capping but would possibly result in instability of the loose chamber. About 30m in total were explored beyond the 6m sump. (Sketch from the logbook)

   Further extensions were made and more surveying occurred over two trips in 2009. A dig in draughting passage at the top end of the cave requires further work: the floor is dropping away. The chamber at the base of the cave, first reached in 1982 was surveyed. In an "upstream chamber", the draught enters through a slot in the roof. A chamber above the final chamber leads to an aven with hanging boulders in the roof and a very low crawl; a drop down into tight passage that links in on the right just after the crawl; a drop down back into the main passage after the crawl.
(2017 and 2018 extensions descriptions edited down from logbook entries by Simon Cornhill & Diane Arthurs.)
   With the 2017 extensions the site was extended by 640m (batch 0373_17_01). The 2018 extensions added 116m, with the 30m extension beyond the upstream sump/duck not surveyed.

Link to entry in the Cave Diving Sump Index.

References: anon., 1982 (logbook); Corrin J, 1983c; anon., 2007d (summer logbook); Corrin Juan, 2007a; anon., 2009c (summer logbook); anon., 2017c (summer logbook); anon., 2017e (Christmas logbook); anon., 2018b (Easter logbook)
Entrance picture :
Underground picture(s):
Video: opening up the base of New Forest, 2017 (YouTube) : Extension Xmas 2017 (YouTube) : Passing the excavated upstream sump, Easter 2018 (YouTube)
Detailed Survey : 1:500 plan pdf (2009)
1:500 plan pdf   1:500 elevation pdf (from 2007) : survey after 2017 extensions : survey after 2018 Easter extensions : sketch of upstream extension Easter 2018
Line Survey :
On area survey :
Survex file : yes (after April 2018) : North Vega system & surrounding caves (after April 2018): (Amended magnetic declination December 2013 to align with Eur79 grid and coordinates altered to fit ETRS89 datum, April 2014.)
Passage direction rose diagram: 30/6/2018