Tesla and SpaceX boss Elon Musk is sending engineers to Thailand to help rescue 12 boys and their football coach from a flooded cave.
Mr Musk said he would be "happy to help if there is a way to do so", after a Twitter user pleaded for him to help the group, who have been underground for almost two weeks.
Mr Musk said SpaceX and another of his firms, The Boring Company, had "advance ground penetrating radar" that is "pretty good at digging holes".
He also tweeted that a "1m diameter nylon tube" could be threaded through the cave network and inflated "like a bouncy castle".
That, he said, should "create an air tunnel underwater against (the) cave roof".
His engineers needed to be on site in Chiang Rai province to appreciate how complex the evacuation was, he said.
James Yenbamroong, who founded satellite communications provider mu Space Corp, tweeted that the "SpaceX team reached out to us today to help connect to Thai govt".
He added: "For pumps, cave has narrowest 70cm cross section. For vertical drill, it's about 1/2 mile down and tricky."
Mr Musk's team could help with location tracking, water pumping or battery power, the Thai government said.
Maybe worth trying: insert a 1m diameter nylon tube (or shorter set of tubes for most difficult sections) through cave network & inflate with air like a bouncy castle. Should create an air tunnel underwater against cave roof & auto-conform to odd shapes like the 70cm hole.
— Elon Musk (@elonmusk) July 6, 2018
Rescue teams, meanwhile, have thrashed through dense forest above the cave complex, looking for a place to start drilling a rescue shaft.
"We want to find the way down – I believe we are close," Thanes Weerasiri, president of the Engineering Institute of Thailand, said.
His engineers are working with the army, exploring an area they believe to be just hundreds of metres from where the boys and their coach are trapped.
"Originally we were exploring it as a way to bring supplies to the children from the back end of the cave, but now it could become more," he said.
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Senior Thai army officer Chalongchai Chaiyakum said up to 200 people were exploring the hill to try to find a workable shaft.
One team travelled 300m down a shaft on Thursday, he said, before reaching a dead end.