Authorities have raised concerns about how much air the 12 stranded boys and their coach have access to inside the cave. The supply has been depleted by the presence of hundreds of rescue workers.
Deputy army Commander Chalongchai Chaiyakham said Friday it was unclear how long the remaining air would last.
Chiang Rai Gov. Narongsak Osottanakorn said on Thursday that rescuers were preparing a three-mile “oxygen pipeline” as part of preparations for the group’s extraction but added that the boys would not be coming out soon.
“You see we are increasing the number of people going inside the cave. So we have to fill it up with oxygen,” Narongsak told reporters.
Rescuers, including international teams, are considering alternative ways to bring the group out before heavy rains hit the country’s north next week which could further hamper the operation.
Rescue alternatives include teaching the boys to dive and then swim out, a highly risky venture, remaining in the cave for months until the wet season ends and flood waters recede, or drilling a shaft into the cave from the forest above.
The boys, aged between 11 and 16, and their assistant coach were found inside the cave on Monday, after nine days underground, hungry but in good spirits. They went missing after they set out to explore the cave on June 23.
Rescuers are deciding how to remove the group but have been slowed down by logistical issues including high water levels inside the cave and narrow, flooded passages which would require the boys to dive alone.
The Thai navy is teaching the boys the basics of diving, with a view to guiding them out through flood waters. However, some of the boys cannot swim and navigating the cave has frustrated even the most expert divers.