Possibilities for continued exploration in the cave include diving in the sump at Copacabana, searching for a bypass to the sump, and exploring the continuation of the collector stream on the far side of the sump.  These were also the goals of an expedition between the 9th and 13th of November, 2011, undertaken by a team of 8 cavers who descended into the cave.  They were assisted by a 14-member surface support team.  The expedition required coordinating the large in-cave and surface teams as well as taking into account  weather and snow conditions.  We also needed to select a cave diver who would be up to such an effort.  We soon found that, because of the depth of the cave, it would not be easy to find a candidate among active divers.  During the search for a diver, we also notified active cavers who occasionally dive.  The exceptional effort involved in the expedition would be significant on a world scale, because cave sumps at such depths have only rarely been explored – in Slovenia only Črnelsko brezno by the world's best team of cavers, Cavex.  Aside from this, the deepest sumps previously explored in Slovenia have been at cave depths of 300-400 m.  The demanding work of diving in Renejevo brezno was carried out by Matt Covington, a member of DZRJL.  The support team was composed of members of DZRJL, one member of DRP Škofja Loka, and one member of JD Dimnice Koper.

The first group of cavers ventured into the cave on November 9, 2011, and on the way replaced 100 m of worn-out rope and established a permanent lower bivouac in the collector passage.  We used this bivouac in preparation for the last leg of the journey to the sump.  All of the necessary equipment was hauled in 11 moderately heavy bags (weighing from 10 to 12 kg), which were brought to the lower bivouac on the 10th of November.  The most sensitive pieces of equipment were two 6-liter 300-bar diving tanks, which were kindly given to us by Matej Mihailovski.  Although there were more than enough opportunities to damage the exposed valves in the squeezes and pits, they successfully endured every knock against the rock.

On the day of 11/11/2011/ a few minutes after 11:11 a.m., we continued along the collector, which had an estimated flow of 300 l/s into the sump.  Some time after noon, Matt donned a 5-mm wetsuit and calmly swam across the lake at the sump, which had a water temperature near 3 ºC.  Once in the sump, he dove to a depth of 10 m and penetrated 30 m horizontally into the tunnel.  After 12 minutes, he returned to the surface.  Within the sump he had surfaced in an 8-m shaft.  The main part of the sump continued on an incline to greater depths, though it also intersected another vertically ascending shaft.  After the dive, we quickly looked for some other side passages that might bypass the sump, or lead to parallel passages, though there was too little time to do more.

We then began the return to the surface with the equipment; the first team exited the cave within 22 hours of the dive.  The last 4 members of the in-cave team exited in the late morning hours of November 13th.  Including the surface team, 22 cavers were gathered at the cave entrance on Kaninski podi, making transport of equipment to the valley fast and efficient.

The expedition went exceptionally smoothly and was practically without problems.  Because Matt used only a little air during the dive, we left both tanks above Copacabana.  The tanks still had a pressure of 200 bars.  In our minds, we are already planning a new dive, which we hope will take us closer to the sump in Boka, approximately 3 km distant.

Therefore, real exploration of the underwater passages within the Kanin mountain range is only just beginning!

In-cave team: Matt Covington, Matic Di Batista, Franci “Franček” Gabrovšek, Tomaž “Garmin” Krajnc, Matija Perne, Mitja “Čot” Prelovšek (all DZRJ Ljubljana), Anže Oblak (DRP Škofja Loka), Rok Stopar (JD Dimnice Koper)

Surface team: Andrej Baraga, Marjan Baričič, Matej Blatnik, Metod Di Batista, Andrej Drevenšek, Diana Grublješič, Franc “Lanko” Marušič, Gregor Pintar, Marina Pintar, Nada Pintar, Aleksandra Privšek, Primož Rupnik, David Senica in Dušan Tominc (all DZRJ Ljubljana)

You can see more photos, a film in two parts and Slovenian version of the report.