MAE SAI, Thailand (AP) — Muddy floodwaters have reached near the entrance of a Thai cave despite attempts to drain the water so rescuers can search farther into the complex for 12 boys and their soccer coach now missing for a sixth day.

Rescuers are trying to find hidden shafts in the green mountainside to access different parts of the cave, while crews also are working to drill wells that could drain the water, which would allow divers to advance into passages filled with water at or near their ceilings. Despite the hard work, rescuers’ progress was fitful at best, with no guarantee the water will soon recede with months left in Thailand’s rainy season.

The governor of Chiang Rai, the northern province where Tham Luang Nang Non cave is located, thanked people in Thailand and abroad for sending their support, including a U.S. military rescue team and U.K. cave divers.

“We will keep our effort up no matter how tired we are,” Gov. Narongsak Osatanakorn said Friday morning.

He said divers had been able to work underwater Thursday but would not elaborate on their progress. The divers have oxygen tanks but still must have enough space between the water and ceiling to surface for air, to ensure their safety in the muddy waters that fill rocky passages, some so tight the divers must bend their bodies to advance through them.

Above ground, four shafts have been located that may allow access into the cave and rescuers were continuing to explore those shafts Friday, Narongsak said.

The team trying to find a way to drain the water dug until 1 a.m. to a depth of 30 meters (98 feet) but did not find any wells, said Ekchawin Longpinit from the Thai Underground Water Department. About a dozen workers were drilling at the same spot Friday morning. “We will continues to drill today, and more drill equipment is being sent so we can also explore” more spots to drill, Ekchawin said.

The boys, ages 11 to 16, and their coach entered the cave after a soccer game on Saturday afternoon, but near-constant rains in the days since have thwarted the search for them. Still, authorities have expressed hope the group could find dry places within the cave to wait, and that they were healthy enough and the cave warm enough to stay safe.

The Thai searchers have been joined by a U.S. military search and rescue team of about 30 people along with British cave experts and several other private teams of foreign “cavers.”