Far Upstream Sump
At the far end of Cueva del Nacimiento is the (Far) Upstream Sump. Dived in the 80’s by Ian Rollands and Rob Parker, and again in 2023 by Martin Groves.
Extract from logbook (Chris Jewell)
Thursday 5th September 2024
diving on KISS sidewinder with 2ltr O2 + 1 x 12ltr 26% and 1 x 12ltr 14/45 + 7ltr ali of O2 for bailout deco.
As the diver was entering the water a leak was found in his KISS O2 MAV. The leak disappeared once the MAV was connected but gas was seen escaping when the MAV button was pressed. Deciding it was acceptable to dive – but monitoring the situation CJ continued. The water level was high and CJ was surprised to find it hard work to get across the chamber to the start of the dive line. Visibility was also disappointingly poor at approx. 4-5m. Martin Grove’s dive line criss crossed the original blue poly prop line which had also survived. After a steady descent to 23m the passage rose before descending to the head of the shaft Martin had reported. The passage was large but the flow was still noticeable underwater. CJ followed Martin’s line down to 43m and along down to 46m depth where the line finished. Attaching his reel the diver began spooling out line along a very large tunnel with clean washed walls and a floor with patches of sand. The passage rose slightly before levelling off after another two belays a distinct right-hand turn was encountered. Preferring the direct route ahead the diver swam forward and into a descending shaft. Soon a gravel floor was spotted and the way on was down through a low arch. It looked like a classic sump elbow but something was wrong – the flow I had been following until now had disappeared completely. Down at 60m I decided this was not the way on and reeled back in, cursing that I hadn’t chosen the right-hand passage. Back into the flow I continued running line in a clean washed passage, fighting hard against the flow in some places, so much so that I had to stop and ensure I didn’t over breathe. At -35m a large rock was wedged across the passage with a route on underneath or over the top. I chose to go under and belayed the line to a convenient rock. Beyond this point CJ found himself in a descending shaft. The walls were checked for alternatives but the only way was down. At 53m depth a large rock was found and the line secured before another 7m of line led me down to 60m depth and the end of my line reel (220m of laid line). My dive computer told me I had a long decompression ahead of me before I could surface but I knew I needed to survey. I swam back up to the -35m wedged rock and pulled out my compass and note book. However as soon as I tried to use the compass it was clear something was up… the dial didn’t turn no matter which way I faced the compass! It was clear I wasn’t going to survey so I headed for home letting the flow take me back towards the start of the sump. After a very short time I was back at the start of my line and decompression stops started at 18m depth. Total dive time was 2hr 40min including 10mins of extra deco just to be safe. At the surface the damage O2 MAV was inspected and after much deliberation CJ decided it wasn’t prudent to dive again on this kit, especially given the likelihood of a deeper dive. It was also clear at this point that the water levels in the cave were much higher than usual and that it had probably rained hard on the surface. So the diver planned to exit, replace the damaged part and see what was happening with the weather on the surface.
Monday 9th September 2024
Water levels were at least 1.5m lower than last time! And the vis looked better so expectations were high. As the gear was all prepped the previous day I was quickly getting changed into my drysuit. This time I had to walk through shallow water to the start of the dive line and don my cylinders. Underwater the vis was better, perhaps 7-8m now and there was no perceptible flow. With bright lights and better visibility, I scanned the walls and ceiling looking for anything I had missed. However, I quickly found myself back at the -35m wedged rock with no other options. Back down the shaft it was then! At 60m I tied on a line reel and descended. A slightly off vertical but very steeply descending passage was followed down to -88m. Lots of arches in the roof were passed only to present another arch lower down. There is no sign that the shaft is going to bottom out any time soon… so there is probably a 100m dive here for whoever wants it! Turning tail, I ascended back to the -35m wedged boulder and began surveying out. The survey was straight forward at first but was complicated when back on the old line – due to lack of legible tags. The chilly 6 degree water took its toll this time and I was shivering by the time I’d decompressed back to 6m. After an hour at 6m (with an extra 10mins just to be safe) I emerged satisfied with my effort but disappointed that no easy way through the sump had been found.