Eighteen divers have gone into a Thai cave to bring out the 12 boys and their football coach trapped there for the last two weeks. The mission to bring the boys out began on Sunday morning, and can get over earliest only by 9 pm, The Guardian reported.

“Today is the peak of our readiness,” said Narongsak Osottanakorn, a former provincial governor leading the operation. The water inside the caves is now at the lowest it has been in the last two weeks, he said. Sunday is the best day to attempt the journey out “because most of the path is walkable”, he said.

Thunderstorms are feared on Sunday and Monday. More rain could again jeopardise rescue efforts. A relatively dry spell in the last few days had helped the rescuers reach the boys and give them food and medicinal assistance. Millions of litres of water have been pumped out of the cave, a Chinese diver told Reuters on Saturday.

Earlier on Sunday, authorities ordered the evacuation of the area around the cave. The boys, aged 11 to 16, and their 25-year-old coach have been stuck in a flooded cave in the northern province of Chiang Rai since June 23.

“Assessing the situation now, it is necessary to evacuate the area for the rescue operation,” authorities said using a loudspeaker. “Those unrelated to the rescue operation, please evacuate the area immediately.”

“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,” Narongsak said. “We have to make a clear decision on what we can do.”

He said the rescuers were still waging a “war with water and time”.

SpaceX Chief Executive Officer Elon Musk tweeted that a team from his company is building a “tiny, kid-size submarine” to help with the rescue.