A Thai governor said today the operation to bring the trapped 12 boys and their coach out of a cave has begun. The acting Chiang Rai governor told reporters “today is D-Day” with 13 foreign and five Thai divers taking part in the rescue.

Thai officials said yesterday they are worried heavy monsoon rain could soon make the job even more difficult and they may need to quickly rescue the boys and the soccer coach from a partially flooded cave by helping them make risky dives to safety.

The boys, ages 11-16, and their 25-year-old coach became stranded when they went exploring in the cave after a practice game. Monsoon flooding cut off their escape and prevented rescuers from finding them for almost 10 days.

Narongsak Osottanakorn, in charge of the rescue mission, said conditions yesterday were currently “perfect.”

“Now and in the next three or four days, the conditions are perfect [for evacuation] in terms of the water, the weather and the boys’ health,” said Narongsak, governor of the Chiang Rai province, where the caves are.

Authorities felt they had a “small window of time to act” to rescue the boys and their coach.

Two divers will be assigned to each child to help them navigate the dangerous, narrow passageways. The water level inside the cave has been brought down to a level where the boys can walk for much of the journey, rather than swim. That will make the operation less risky.

Heavy rain is in the forecast and oxygen levels in the cave have been dropping to dangerous levels.