Rescue divers are making progress through a key passageway deep inside a flooded mountain cave complex in Thailand where 12 boys and their football coach have been missing for more than a week.
The divers from a Thai navy Seal unit were within 500 metres of a chamber containing an elevated rock mount which may have provided the boys with a refuge.
The boys, aged 11 to 16, and their 25-year-old coach, entered Tham Luang cave in Chiang Rai province on 23 June.
Heavy rains flooded key passages of the cave and blocked the way out.
Progress has been slow, as muddy water has risen to fill sections of the cave and forced the divers to withdraw for safety reasons.
When water levels dropped on Sunday, they went forward with a more methodical approach, deploying a rope line and extra oxygen supplies along the way.
Doctors have said the boys could survive for days without food, but their survival would depend on whether they found water clean enough to drink.
In addition to the divers, teams have been working to pump out water as well as divert groundwater.
Other efforts have focused on finding shafts on the mountainside which might serve as a back door to the blocked-off areas where the missing may be sheltering.
Teams have been combing the mountainside looking for fissures which might lead to such shafts.
Several have been found and explorers have been able to descend into some, but so far it is not clear whether they lead to anywhere useful.
National news has been dominated by updates from the search, which involves more than 1,000 personnel, including rescue teams from Britain, the United States and elsewhere.
Additional reporting by agencies
