Meanwhile, army trucks, doctors, rescue workers and journalists continued to pour into the site.

Those relatives have maintained a constant vigil at the base camp, which is an ocean of thick, oozing mud that slows down everyone and everything, since they first went missing

No one knows exactly when the boys and their coach will get out, or by what method.

But the race to get them out will escalate on Wednesday as rescue workers brace for more heavy rains that will likely stymie “plan A” to pump water out of the caves.

The base camp set up to service rescue workers – and the hundreds of journalists from around the world who have descended on the muddy site.

The Tham Luang caves are just a short drive from Mae Sai, a small town famous for being part of the notorious “golden triangle” heroin region (and not much else).

But getting to the edge of the cave requires an uphill trek through the thick, brown ooze that slows down everything and everyone on roads crowded by Humvees and army trucks.

Huge pipes spew water down the sides of the road and into the banana fields, trying to dry the place out as Thai authorities and rescuers from around the world scramble to rescue the 12 boys and their coach.

But when the rains hit, much of that pumping work will likely be undone and there is every chance the flooding will worsen, potentially forcing authorities to abandon plan A and, instead, get the boys out through narrow, underwater passages with the assistance of expert divers.

With suggestions that none of the boys, aged 11-16, can swim, this is also considered the most difficult option.

The alternative is the boys may have to remain in the caves for months – possibly as late as October when the rainy season ends - at which point the 13 could walk out alongside the military doctors who have volunteered to remain in the cave with them.

Thai Interior Minister Anupong Paojinda, a member of the ruling military junta, flagged the prospect of the boys using diving gear while being guided by professional divers.

The boys are described as healthy and are being looked after by seven members of the Thai navy SEALs, including medics, who were staying with them inside the cave. They were mostly in stable condition and have received high-protein drinks.

Anupong said the boys would be brought out via the same complicated route through which their rescuers entered, and he conceded that if something went awry, it could be disastrous.

"Diving is not easy. For people who have never done it, it will be difficult, unlike diving in a swimming pool, because the cave's features have small channels," he said. "If something happens midway, it could be life-threatening."

On Tuesday Anand Surawan, a navy captain, suggested that the boys would be sent "additional food to be sustained for at least four months," while they trained to dive and rescuers continued to drain water with high-pressure pumps.

with AP