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
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. These 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 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.
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)
See 025 Risco
Entrance picture : yes
Underground picture(s): streamway Mavrino Inlet male gyas titanus
Detailed 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)
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.); separate file (Coordinates altered to fit ETRS89 datum, April 2014.)
Passage direction rose diagram (Patrick Warren): yes, with Risco and Tiva