What next for the trapped Thai boys?

Rescue workers are facing the crucial task of getting 12 boys and their football coach out of a flooded cave in Thailand.

The group had already spent nine days in the cave with no food or light when they were discovered on Monday.

But the authorities say they might have to stay put for weeks or even months until they can escape safely.

One possibility is that the boys could be taught to swim through the cave's tunnels using scuba diving equipment.

"The option to bring them out by diving is the quickest but it's also the most dangerous," Anmar Mirza, national co-ordinator of the US Cave Rescue Commission, told the BBC.

It took days for some of the world's best divers to reach them, and the novices would be forced to contend with fast-running torrents, poor visibility and narrow passages.

Rescuers could supply full-face masks and install dive lines, oxygen tanks along the way and glow sticks to light the path. But experts warn the risk would still be great.

Another option would be to wait for the flooding to subside so the group could leave on foot. But this could take months, as the monsoon season sets in.

Read more: How will rescuers free the Thai boys?

Rescuers are also considering trying to drill into the chamber and airlift them out - again a difficult task.

The boys, aged between 11 and 16, and their 25-year-old coach, are huddled on a small rock ledge. The environment is wet, so they must keep warm and dry, or risk hypothermia.

Rock falls are a threat, but the main concern for rescue teams is rising flood levels. Storm waters could complicate access routes, threaten the supply of air into the chamber and hamper evacuation attempts.

While they wait to be freed, the boys must remain calm and stay on the ledge, says Andy Eavis, retired head of the British Caving Association.

If not, they could easily fall down a drop in the rock, or get washed away by the water.

Read more: What to do to survive underground

"Crawling around in the dark is the biggest problem," Mr Eavis told the BBC.

Much-needed food and medical supplies - including high-calorie gels and paracetamol - reached the boys and their coach on Tuesday.

"(We will) prepare to send additional food to be sustained for at least four months and train all 13 to dive while continuing to drain the water," Navy Captain Anand Surawan said, according to a statement from Thailand's armed forces.

Officials say most of the group are unhurt, although some are weak or have minor injuries. A doctor and nurse are with them, and will decide whether they are strong enough to be moved.

In the meantime, divers have been taking hundreds of oxygen tanks into the cave, and are preparing to establish a base camp inside the chamber.

"What is terribly debilitating in these situations is the darkness," says Mr Eavis.

The boys may have had torches or lights on mobile phones, but they have potentially been sitting in the dark for hours, he says.

So rescue teams have been taking lighting into the chamber, and keeping the group company.

Divers have also been preparing power and telephone lines to enable the boys to speak with their parents.

Everything considered, they seem to be doing fine so far.

"They're mentally stable which is actually pretty good," Ben Reymenants, a Belgian diver helping with the rescue operation, told AFP news agency.

"Luckily the coach had the sanity of mind to keep them all together, huddled together to conserve their energy, that basically saved them."