On June 23, 12 teenag-ers (between the ages of 11 and 16) and their 25-year-old coach were trapped in Thailand cave below a mountain, all members of White Boar football club. They were first discovered by two British divers on July 2 after an intensive search. But on Sunday four of them were extracted, while four were retrieved on Monday. And yesterday, Tuesday, the remaining four and their coach were successfully rescued from the cave by a team of inernational and local dives after 18 days underground. The Thai cave complex where 12 boys and their football coach became trapped is a snaking system of caverns and crevices which pose a range of problems for rescuers. Some stretches of the Tham Luang cave are more than 10m (33ft) high, while others are a tight squeeze through water-filled passages. The death of an experienced former Thai navy diver, on Friday, who was part of a team trying to supply the aboys' cave with oxygen tanks, emphasised the dangers of the mission. The group of boys and their coach were exploring the caves when a sudden storm caused the passageways to flood, trapping them inside. They had spent nine days in the cave with little food or light when they were discovered on Monday 2 July by two British divers. Rescuers initially wanted to keep the group supplied underground until the end of the rainy season - which would have taken months. But with the forecast of heavy rains, and the risk of water levels rising, an operation is now under way to bring them out. How the boys escaped? Rescue divers with specialist breathing equipment reached the group through a series of water-filled passages. The boys were being taken out the same way. According to BBC reports, two divers accompaned each boy, one holding the boy close under his body and the other diver following behind. The divers guided them through the dark using ropes. In narrow sections, rescuers had to take off their air tanks and squeezed the boys and the tanks through. The diving option was considered extremely dangerous by some, but experts say the priority was to get the boys out before the rains bring more flooding and debris into the cave system. What were the dangers down there? The boys, aged between 11 and 17, and their 25-year-old coach have been huddled on a small rock ledge. The environment is wet, so they were kept warm and dry or risked hypothermia. There were concerns about the level of oxygen in the air in the space where the boys were trapped. Officials said at one point that the level of oxygen in the air had fallen to 15 per cent. The usual level is 21 per cent, reports the BBC. Rescuers had transferred about 100 oxygen tanks to the cave to help improve the air supply after they were found. Thai diver PO Saman, who had been helping transfered the tanks got into difficulties on the way back and did not have enough air himself. He died after losing consciousness in one of the passageways and his colleagues could not revive him. Finally, the dramatic three-day rescue of a Thai youth soccer team from a flooded cave came to an end yesterday, when the last boy and coach were plucked from the underground cavern more than two weeks after they were trapped.