Chiang Rai Governor Narongsak Osotthanakorn said the chimney, discovered during a survey on the mountain, is located on the Mee cliff in the northern section of the cave.
Police paratroops from the Naresuan camp lowered ropes 40 metres inside and they landed on muddy soil, he added. It is not clear yet whether the area is part of another chamber of Tham Luang.
The chimney is on the opposite side of a location called Pattaya Beach that is believed to be where the boys and their coach might have reached.
The 13 entered the cave last Saturday afternoon (June 23) and have been the subject of a massive search and rescue effort hampered by flooding and persistent downpours in Mae Sai, near the border with Myanmar in this northern province.
Thai and foreign rescuers have been trying to find other entrances to the cave as the main access route has blocked by floodwater despite efforts to pump it out.
A video clip posted online by the Navy Seal team showed the rapid flow of water through a passage that divers had been able to navigate earlier, but it was blocked by water again yesterday morning (June 29).
Workers are pumping water out of the cave and are bringing in more generators and electrical equipment to facilitate the mission. The water level was rising by three centimetres an hour yesterday morning after heavy rain resumed on Thursday night (June 28).
Other teams were drilling into the soil close to the cave in another attempt to drain water from Tham Luang. They sank their first hole 30 metres but did not find any wells, said Ekchawin Longpinit of the Underground Water Department.
“We will continue to drill, and more drilling equipment is being sent” to explore other spots, he said earlier yesterday.
A team of Seals and three British divers attempted to dive to a chamber on the way to Pattaya Beach but returned because of the strong current, according to a Royal Thai Navy report.
Police dropped plastic boxes containing food and first-aid packages inside shafts in the hope that they might reach the boys and their coach. Each box includes food, a light, a map with a pen for them to mark their location, a bottle of water and even a mobile phone in case connections to contact rescuers can be made.
Police hope that if the packages reach the group, they could mark their location on the map, place it in a box and float it back to reach the hands of the search teams.
Meanwhile, his Holiness the Supreme Patriarch led a mass prayer yesterday for the missing 13.
The prayer for the missing boys aged 11-16 and their 26-year-old coach took place in the evening at the Royal Plaza in Bangkok as part of a public prayer dedicated to the late King Bhumibol Adulyadej and Her Majesty the Queen as commanded by His Majesty the King.
The ceremony, which was broadcast live, was attended by government figures headed by Prime Minister Prayut Chan-o-cha who yesterday morning travelled to the northern province to give moral support to the families of the missing and rescuers.
Early in the day, tens of thousands of students and teachers at schools nationwide conducted prayers and meditations to send blessings to the local football team nicknamed “The Wild Boars”.
In Songkhla, Thai Muslims joined the nation in praying for the safety of the missing group and vowed to keep sending blessings until the boys and their coach were returned safely to their families.
A group of independent scholars, meanwhile, has suggested drilling into the area behind Tham Luang cave in Chiang Rai's Mae Sai district to create a new passageway for attempts to locate 12 boys and their football coach.
The group comprises personnel from the Mae Fa Luang Foundation, academics from Chiang Rai Rajabhat University, officials from the Royal Irrigation Department, the Mineral Resources Department and a group called the Northern Offroad Network.
They have set up a makeshift operations centre at Ban San Pha Sak in tambon Pong Pha of Mae Sai district to brainstorm ideas to support the search and rescue operations.
The group surveyed the rear end of Tham Luang cave known as Martin’s shaft – a crevice which is about 10 kilometres west of the cave’s entrance.
The group is trying to pinpoint possible points of access to determine if a passageway could be drilled into the cave. Their findings will be presented to the agencies involved in the rescue operation.
Songwit Kaewmahanil, a Mae Fa Luang Foundation official, said that foreigners who have explored the cave told him that they saw light streaming through towards its end, indicating that may be an area where a new tunnel could be drilled.
Chiang Rai governor Narongsak Osotthanakorn said rescue teams yesterday surveyed a cave called Monk’s Series which is located north of the entrance of Tham Luang cave. They abseiled into a ceiling crevice which is about 40 metres deep. However, it was not clear if the crevice would lead them to the missing team.
Gov Narongsak denied reports that a rescue volunteer was electrocuted while helping install a power line yesterday afternoon.
The man only passed out and was taken by ambulance to an army hospital and was in a safe condition, the governor said.
The man was a volunteer from Ubon Ratchathani, there to assist with the search for the 13 missing footballers, he said.
The government will also ask Myanmar to close its Sai River dam temporarily which will help reduce underground water, which in turn will improve drainage of flood water in the cave, Gov Narongsak said.