Thailand's specialized Navy divers re-entered Tham Luang Nang Non cave on Tuesday to look for a children's football team that has been missing for three days. The missing group includes 12 boys aged 11 to 16 and their 25-year-old football coach.
"We must find the children today. We have hope that they are alive somewhere in there," provincial governor Narongsak Osottanakorn told the Reuters news agency.
Authorities found a motorbike and bicycles belonging to the boys in front of the entrance of the sprawling cave, and footprints, handprints, and shoes and bags inside the cave complex. Rescuers believe the group was cut off from the entrance by flood waters due to the start of the rainy season.
Heavy rain also brought the rescue effort to a halt on Monday, with water levels rising almost to the ceiling inside one of the chambers.
"We hope that the water level has gone down, but we will have to see," Navy Lieutenant Naponwath Homsai said on Tuesday. "Today we will try to find passages under the water that hopefully will lead to other chambers."
Underwater drone to help with the search
Parents of the missing, many of whom are camping outside the cave, took part in a traditional prayer ceremony on Monday evening, playing drums and gongs, and holding up fishing nets to symbolically fish out lost spirits from the cave.
In addition to divers, authorities have used helicopters and foot parties to find other ways into the mountainside cave from the surface.
Rescuers also said an underwater drone would be deployed later on Tuesday.
"We will bring the underwater robot to help survey the area to know how big and how deep the cave is to help the diver," said Sawangtit Srikitsuwan, an aerospace and marine engineer at Bangkok's King Mongkut's University of Technology.
The Tham Luang Nang Non cave complex is a popular tourist site, but often floods during the June-October rainy season. Officials said tourists have been trapped in the cave and rescued in the past.