On 25th of May a team of scuba divers conducts an attempt to pass the syphon in the “Golemia Izvor” water cave, near the village of Kipilovo, Kotel Municipality, District of Sliven, Bulgaria.
The known information about the cave up to the present moment is that it starts with a dry 20 meters long gallery which goes into a 125 meters long syphon. There is a narrow passage which is hard to pass at the lowest part of the syphon (about 8 meters deep at dry weather conditions) which is situated about 10 meters from the beginning of the syphon. After this passage the syphon expands and ends into a steep, muddy gallery which is impossible to climb without a special equipment. There is a very small air dome in the middle of the syphon.
One of the divers enters the syphon alone about noon and since then he is missing. In the meantime, the water level starts to raise. The missing diver is an open water scuba diving instructor with no cave training. He carries two gas tanks – one of 10 liters and one of 3 liters and uses no leading cord which is an essential part of the cave diving.
After the control time expires the rest of the group escalates a signal to the emergency phone line – 112 about 17:30 on the same day.
The Bulgarian Cave Rescue team is informed late in the evening and starts the procedure of organizing a Cave rescue operation. Immediate action is impossible due to the adverse weather conditions combined with the complicity of the incident.
A group of cave rescuers reaches the cave in the morning on the next day – 26th of May and establishes that a water outs the cave entrance at a rate between 2 and 3 cubical meters per second which still prevents the starting of the rescue operation.
After a briefing with the local authorities and the police all of the participating teams are ready to start the operation at the moment when the weather conditions allow this.
On 28th of May after a forecast that promises stable weather conditions during the next days, the riverbed in front of the cave is being cleaned and the water started to be pumped out of the syphon using four mobile pumps. The water level of the syphon starts to lower but a dive is still impossible.
On 29th of May the pumping and the cleaning continues as well as searching the region for a possible water sources that supply the syphon with water and higher cave entrances. Diving into the syphon is still impossible.
On 30th of May a team of cave divers from Plovdiv conducts 3 dives inside the syphon and passes about 130 meter length reaching a depth of about 19 meters. No dry galleries were found and the visibility was extremely limited by the muddy water at the parts reached.
On 31th of May 2 dives are conducted. During the first 150-160 meters of length are reached with a total depth of 36 meters, but the lost diver was is not found. During the second dive a detailed check of the syphon is made to about 120 meters but again without success.
The rescue teams continue their efforts to complete the operation.