Officials prefer to get the boys out as soon as possible because heavy rain expected by Saturday almost surely will raise water levels again in the cave, making passage in some areas even more difficult, if not impossible.

They are hoping that an upgraded draining effort can lower the water in an area where it is still at or near the ceiling. The idea is to get some headroom so the boys would not be reliant on scuba apparatus for a long stretch and could keep their heads above water.

The navy has released videos of the boys, showing them smiling and interacting with the personnel sent into the cave to bring supplies, treat their injuries and keep them company.

One Thai navy SEAL team member who spent time with the boys said the young soccer players "were always asking about the World Cup." ''I told them that all the big teams had gone home," the navy SEAL member said.

Seeing the boys has boosted the mood of their family members, and officials are working to install an internet cable to the cave so that parents can talk to their children.

Kian Kamluang, whose 16-year-old son, Pornchai, is in the cave, said she had thought there was a 50 percent chance that her son would be found.

"It's like he has been given a new life," she said, adding that she'll never let her son go into a cave or near water again.