THAI navy divers leading the search for 12 boys and their football coach in a cave have failed to make much headway in their effort to push through the murk of a half-mile-long chamber to what is thought to be a clear area where the missing may be sheltering.

Rescuers say they hope the boys aged 11 to 16 and their 25-year-old coach have reached a rock mound in an underground chamber.

No contact has been made with them since they went to explore the sprawling Tham Luang Nang Non cave in Chiang Rai province after a soccer game on June 23.

Sunday’s reckoning comes after a break on Saturday in the constant rainfall had lowered water levels, bringing hope that the muddy water inside the crucial but clogged chamber would recede and expedite divers’ movement forward.

The search effort in the northern province of Chiang Rai has been going slowly, largely because flooding has blocked rescuers from going through chambers to get deeper into the cave.

Pumping out water has not solved the problem, so greater effort has been made to find shafts on the outside of the cave that might serve as a back door to the blocked-off areas where the missing may be sheltering.

Australian police and military personnel were deployed on Saturday to join other multinational teams of experts. Their plight has gripped the country and led to an outpouring of support and hope.