Updated 19th February 1999; 14th May, 12th November 2002; 6th November 2003; 8th October 2005; 1st March, 29th September 2006; 17th November 2007; 19th November 2008; 18th May 2009; 6th January, 1st October 2011; 23rd April 2012; 6th March, 3rd May, 22nd September 2022

   The entrance pitch of 6.5m can be free climbed, but can be bypassed completely (as of May 2009) by entering through an excavated crawl to the left. (It was noted in August 2022 that the shaft entramnce was collapsing.) The routes lead into the streamway or a few high level chambers can be reached. After a short crawl, water from a sumped passage on the right is met and for the next 500m the cave is a sporting vadose streamway. At the end is an 18.6m pitch into the final chamber of Sima-Cueva del Risco. (This was bypassed on the left in 2005 and the first through-trip to Risco bypassing the pitch completed on Aug 1st 2006- see survey below).

   On the left of the streamway, 30m before the pitch, a small passage leads into a large fossil gallery, Mavrino Inlet,  which soon chokes. From this passage the 2005 (and later) extensions lead off.
   Gulag Gallery starts as a calcite-floored side passage on the left at the start of Mavrino Inlet. This goes for about 100m with signs of previous entry to a low point which was dug out to a small chamber and a 5m free climb to a bedding plane, ending at the top of a meander passage. This enters a crawl with boulders that continues past holes in the floor and enters walking size passage with stal and passages in the roof. The passage rises to near the surface with tree roots: Gulag Gallery has almost come full circle back to the Oñite entrance with a length of 446m.
   184m of extensions on the opposite side of Mavrino Inlet provided the Sala Carballo Pitch Bypass.
   The First Circle - known passage - was surveyed in 2005 and increased the length of the Risco System to 9859m.
The survey was "completed...beyond stal bridge" beyond Sala Caballo on a trip in the summer, 2011. Forty six metres were surveyed.
    At Easter, 2022, a wet inlet, 4.5m up (Mental Illness Inlet) was bolted into on the eastern wall of the Mavrino Inlet. The inlet is generally a tall, rift passage with a stream in the bottom. Progress is made mainly by traversing at high level. After a couple of hundred metres, the passage splits, the largest ending in boulders and tree roots. The water comes from a small inlet passage where a blocking boulder could easily be removed. Mental Illness Inlet is drawn on the updated 2022 Easter survey. The centre line on the Survex/Aven file is 0025-22-01 and 0025-22-02.

Link to entry in the Cave Diving Sump Index.

References: anon., 1974a (survey); Kendal Caving Club and Manchester University Speleological Society, 1975; Fernández Gutiérrez J C, 1975; anon., 1975a; Manchester University Speleological Society, 1982 (survey); Mills L D J, 1981; Corrin J S and Smith P, 1981; García José León, 1997 (survey and photo); pers comm (email 13/5/02); anon., 2005b (Easter & summer); anon., 2006a (February logbook); Corrin Juan, 2006a; anon., 2006d (summer logbook); anon., 2008f (autumn logbook); anon., 2009a (Easter logbook); León García José, 2010 (Volume 1 and Volume 2) (survey); anon., 2011d (summer logbook); anon., 2022b (Easter logbook); anon., 2022c (summer logbook)
See 025 Risco
Entrance picture : yes
Underground picture(s): streamway : Mavrino Inlet : male gyas titanus : Mental Illness Inlet
Detailed Survey : Original 1974 survey
preliminary pdf of 2005 extensions with original passage  Resurvey complete early 2006
from rescue site (Risco, Tiva and Oñite)  low res  high res
On 2009 survey of Risco and Oñite (Peter Smith) : For later surveys, see Risco 0025
Line Survey :
On area survey : 1975 Ozana area map. Not a lot of detail. low res  high res
Survex file : on Risco file (Coordinates altered to fit ETRS89 datum, April 2014.)
Passage direction rose diagram (Patrick Warren): yes, with Risco and Tiva