Using Northern Diver CNX neoprene drysuits, this team of divers has explored Nestelberg cave in Austria. Here follows an extract from their report. This team are also working elsewhere in Austria and we will bring you reports as they are published.
This Karst cave consiststs of Gutensteiner limestone and lies 520m above sea level. It is the biggest known Karst cave in the area of Lackenhof am Ötscher and is an all year round active water source, pouring between 40 and 2000 litres of water per minute.
In 1985 a flood caused debris and rubble to be moved from the entrance area to outside the cave, changing the appearance to what we see today. Since that event, the cave entrance has a height of 12m.
The cave's course runs first in an easterly direction for approximately 10 metres which leads, after a right-angled branching to the north, across a further 10 metres where the cave becomes submerged. Here, the roof of the cave touches the water surface. The water level in the by accessible above water cave course varies between 0.5 and 1.5m. Within this area of the cave the beautifully laminated Gutensteiner limestone is noteworthy. Below the water surface the cave runs mostly in a northerly direction with an inclination of approximately 45 degrees. The average water temperature is approximately 6 degrees C.
CTDR Site Activities:
The team have been diving in the cave since 1992, after a tip from a Speleologist who had investigated it 30 years before.
Michael Jurkovics and Marcus Kalmar reached a depth of 30m using compressed air.
Michael Jodl joined the diving team. After some dives in other caves the team reached a depth of 40m in Nestelberg Cave. They recognised that a far deeper attempt with acceptable risk would be possible only by using mixed gas (Trimix). Shortly afterwards the team completed Trimix training.
Mapping the cave to a depth of -50m. This involved 5 Trimix dives taking place that year, amongst other dives.
Franz Huber entered the Team. Michael Jurkovic abandoned cave diving for personal reasons. A Trimix dive (scheduled for November which was planned to reach a depth of -75m) failed at a depth of -60m at a close constriction which seemed to be impassable for divers with back mounted gear. The cave was constricted at that point with sand, crushed stones and small boulders. To dig in the cave to widen the constriction seemed to be dangerous with the depth and conditions.
Between 1996 and 1999
The Team used the cave for training reasons, undertaking 35 Trimix dives during that period.
12 penetrations reached depths below -55m, five of them reached the end of the passable range.
1998 for testing reasons we absolved (as far as we know) the (as far as we know) first Neon cave dive in Europe, and reached a depth of -55m.
1999 Franz Huber failed with an attempt to pass the constriction with sidemounts using Trimix. After that dive the team finished the measurement of Nestelberg Cave to a depth of -60m.
During a test dive (for another project) in December, the team found the unpassable constriction noticeably widened.
After the obvious change in the cave landscape we planned an attempt to reach a depth of -80m in January.
This was with Anton Krischanitz as surface support, Julian Kalmar as surface photographer, Michael Jodl as support diver, Franz Huber and Marcus Kalmar as Trimix divers. The team finally reached a depth of -75m at Nestelberg Cave. After the last constriction follows a right hand bend, thereafter a steep, narrow corridor with slabs (platters of rock) hanging from the roof. The passable part of the cave ended in a small room which we called "Room of insight". The ongoing very narrow corridor seemed to be plain (in the sense of not steep) not to go deeper, and was partially blocked with massive boulders and not passable. At last we discovered the End of Nestelberg Cave.