Twelve Thai boys and their football coach who were rescued by divers after being trapped in a flooded cave for over two weeks spoke publicly today of their incredible ordeal.

Appearing at a press conference beamed worldwide, the "Wild Boars" team members appeared healthy and happy despite the nine days they spent in the dark before being found by an international rescue team and extracted days later.

A packed crowd greeted the youngsters after they were discharged from hospital in Chiang Rai, and watched as they played with footballs on a small makeshift pitch before taking their seats.

"It is a miracle," Adul Sam-on, 14, said of the rescue, as the boys were gently quizzed about their terrifying experience by a moderator before dozens of cameras.

The team had no food at all until they were found deep in the complex, surviving only on water that dripped down the side of the cave.

"We drank water that fell from the rocks," said Pornchai Khamluan, 16.

Coach Ekkapol Chantawong told reporters that they prayed before the first night they went to sleep in the cave, and later tried to find a way out by themselves.

"We tried to dig out as we thought we cannot only wait for authorities to get us," he said.

Doctors said all 13 were in good physical and mental health after recuperating in hospital.

The briefing was tightly controlled, with experts warning of possible long-term distress from their ordeal inside the Tham Luang cave in northern Thailand.

The public relations department in Chiang Rai solicited questions from news outlets in advance, which were forwarded to psychiatrists for screening.

Thailand's junta leader Prayut Chan-O-Cha urged the media to be "cautious in asking unimportant questions" that could cause unspecified damage.

Interest in the saga has been intense, with film production houses already eyeing a Hollywood treatment of the drama.

Doctors have advised families of the players, aged 11 to 16, that they should avoid letting them contact journalists for at least one month.

'Happiest day of my life'

The boys, who will return to their families Wednesday night, announced their plan to temporarily ordain as monks to honour the death of Saman Kunan, a Thai Navy SEAL who died during the rescue.

Khameuy Promthep, the grandmother of 13-year-old Dom, one of the boys rescued from the cave, told AFP at their family shop in Mae Sai near the Myanmar border on Wednesday that she was very excited.

"This is the happiest day of my life," she said.

The daring Thai-led international effort to rescue the team captivated the world after the football team walked into the cave on June 23 and were trapped by rising floodwaters.

After nine days without food, they were found emaciated and huddled in a group on a muddy ledge by British divers several kilometres inside the cave complex.

One of the boys said that after they were found they played games, including checkers, and that a Thai Navy SEAL staying with them won most of the time.

"We called him king of the cave," said 14-year-old Ekkarat Wongsukchan, known by his nickname Bew.

Rescuers debated the best plan to bring them out but ultimately decided on a risky operation that involved diving them through waterlogged passages while they were sedated to keep them calm, and carrying them out in military-grade stretchers.

Not even the foreign cave diving specialists who took part were sure the mission would work. Many expressed huge relief after the final five were rescued on July 10.

'Pedo' row

Further attention was drawn to the rescue by a highly public row between entrepreneur Elon Musk and a British caver who took part in the rescue.

Tesla CEO Musk called Vernon Unsworth a "pedo" in an extraordinary social media attack, after the caving expert had ridiculed Musk's plan to recover the trapped group using a miniature submarine.

Musk on Wednesday apologised to Unsworth over the slur, for which he had provided no justification or explanation.

"(H)is actions against me do not justify my actions against him, and for that I apologize to Mr. Unsworth and to the companies I represent as leader," Musk wrote on Twitter. "The fault is mine and mine alone."

Musk's attack on Unsworth had drawn widespread outrage and briefly sent shares in Tesla tumbling.

Towards the end of their introduction to the world the "Wild Boars" were asked what they wanted to be when they grew up. Many said they want to be either professional footballers or Thai Navy SEALs.

"This is my big experience that makes me stronger," said 11-year-old Chanin Wiboonrungrueang.