Finnish diver Mikko Paasi has been assisting rescue workers since Tuesday and spoke with Yle on Wednesday morning.
Paasi said the boys were able to hear the sounds of barking dogs from outside the cave, raising rescuers' hopes that there is a crack in the cave which could lead to reaching the trapped young footballers and their coach.
"The kids said they have heard animal sounds, for example dogs barking, inside the cave. That has raised hope that there might be some kind of crack that leads into the cave," Paasi said.
"Now we're trying to find another way into the cave than diving or drilling a tunnel," he said, explaining that the search and rescue team was now trying to locate where the sound originated. That is a difficult task, he said, because sound is reflected around the cave walls.
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Now mountain climbing experts are looking for crevasses on the cave's rocky exterior surface while others look for interior routes into the cave.
Boys seen in video on Wednesday
On Wednesday the Thai Navy released a video of the boys who were seen bundled up in foil blankets, smiling and laughing as they each introduced themselves.
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The dozen boys and their football coach have been trapped in the cave by rising water for the past eleven days, and were discovered by rescuers on Monday.
Locals are worried that their rescue may be hampered by more rain, as the rainy season has just begun.
Paasi told Yle on Wednesday that the water in the cave was not rising at the moment but said water levels could rise in the coming days.
"It's not raining right now and the pumps are working at full capacity," he said.
The cave's low water levels have given rescuers hope the boys could be rescued by divers but Paasi said the possibility of cracks in the cave have raised hope they could be extracted more safely that way.