This is how the divers perform the complicated cave rescue

What is happening at the cave?

A team of 90 expert divers - 40 from Thailand and 50 from overseas - has been working in the cave system. In a BBC article, the complicated dive rescue is explained.

Getting to and from where the boys are has been an exhausting round trip, even for the experienced divers.

The process includes a mixture of walking, wading, climbing and diving along guide ropes already in place.

Wearing full-face masks, which are easier for novice divers than traditional respirators, each boy is being accompanied by two divers, who also carry his air supply.

The toughest section is about halfway out at a section named "T-Junction", which is so tight the divers have to take off their air tanks to get through.

Beyond that a cavern - called Chamber 3 - has been turned into a forward base for the divers.

There the boys can rest before making the last, easier walk out to the entrance. They are then taken to hospital in Chiang Rai.

In an indication of how dangerous the journey can be, a former Thai navy diver died in the caves on Friday. Saman Gunan was returning from a mission to provide the group with air tanks when he ran out of oxygen.

He lost consciousness and could not be revived. His colleagues said they would "not let the sacrifice of our friend go to waste".

This is a hugely high-profile rescue attempt and Thailand knows the world is watching. It has embarked on a dangerous option but believes it's the best for bringing the group out alive.

It has assembled a team of internationally renowned divers and so far their expertise has brought four boys - thought to be the weakest - back to their families.