CHIANG RAI, Thailand — Having failed to find any sign of 12 boys and their soccer coach during a week-long search of flooded cave complex in northern Thailand, rescuers held out hope on Saturday that the group could have found safety on a rocky mound in one of the chambers.

Divers from the Thai navy’s elite SEAL unit were groping their way through the murky waters filling passages of the 10-kilometer underground maze of the Tham Luang cave, as the rescue effort turned increasingly desperate.

International rescue teams, including 30 US military personnel, have joined the search for the junior soccer team, which went missing last Saturday.

Divers were still some way from the potential safety spot, called “Pattaya Beach” after one of Thailand’s best known tourist destinations. “The distance we’ve got still got to go is probably two to three kilometers,” Narongsak Osottanakorn, governor of Chiang Rai province, said.

Meantime, a police search party has entered the cave from the surface, having drilled a 50-meter long shaft from the mountainside. Survival boxes, filled with food, water and torches, had been dropped down the shaft on Friday, but by Saturday it was wide enough for rescuers to be lowered into the cave.

Deputy Police Chief Wirachai Songmetta said that search party has, as yet, been unable to reach the underground chamber that could be the best hope of survival for the boys.

Aside from bicycles and soccer boots left near the cave’s entrance, and some handprints seen on the walls, the searchers have found no trace of the boys, aged between 11 and 16, or their 25-year-old assistant coach.

Still, rescuers believe the boys have a chance of surviving, and could have access to fresh water inside the cave, and medical teams were practicing drills to treat survivors, and airlift them from a makeshift helipad.

Relatives kept a vigil, with prayers led by a Buddhist monk, near the mouth of the cave.

“I am still hopeful and hope the children will come out safely,” Kampon Paree, 39, an uncle of three of the missing boys, said.

Water levels inside the complex labyrinth of tunnels finally dropped thanks to dozens of pumps set up to drain the floods even as heavy rain continued to pound the area near the Myanmar and Laos borders.

“The situation is better today than yesterday and the day before. Water has receded considerably and we are pumping out water in all chambers (near the entrance),” Narongsak said.

The group likely has access to fresh water — either dripping in through rocks or rushing in through the entrance -- but experts warned that runoff water from nearby farms could carry dangerous chemicals or bacteria.

“If they drink the water in the caves and it makes them sick it could hasten the problem that they are in, but if they don’t drink it then they are also in trouble,” Anmar Mirza, coordinator of the US National Cave Rescue Commission, said.

But even without food he said young, athletic boys could “easily live for a month or a month and a half” with the main challenge their mental resolve.

“The biggest issue that they are facing right now if they are alive is psychological because they don’t know at what point they might get rescued,” Mirza said by phone from the US state of Indiana.

The dramatic weeklong rescue has galvanized the nation and prompted emotional outpourings online from well-wishers praying for their safe return.

Cartoon images of the smiling boys being found by divers circulated along with messages for the team: “Stay Strong, We are Coming” and “Don’t Give Up”. — Agencies