But a rainy season downpour flooded the tunnels, trapping them. "Don't worry anymore. I am safe now", 13-year-old Panumas Saengdee said in Thai, per ABC.
The hunt to find them turned into an global rescue operation involving thousands of people, from specialist divers to an army of local volunteers.
Some talked about what they would like to eat and another said "thank you" in English.
"I want pork knuckle rice", said 13-year-old Duangpetch Promtep.
Prime Minister Prayuth Chan-ocha said on Thursday worldwide members of the rescue team would be given a "Thailand Elite" card worth 500,000 baht ($15,000) with benefits including a 5-year visa in thanks.
Asked if their actions might be seen as insensitive at such a delicate time, co-producer Adam Smith said: "There's going to be other production companies coming in so we have to act pretty quickly".
The boys and their coach were invited to attend the final by world soccer governing body Federation Internationale de Football Association, but they are unable to go for medical reasons.
All 13 were brought to safety over the course of a three-day rescue, organised by Thai navy SEALs and an global team of cave-diving experts. Some had pneumonia when they were brought out of the cave but were recovering.
Volanthen told the BBC of the moment he found the boys, saying that a lot of media reports had suggested that it was through "luck" which was "absolutely not the case". "He told me when I visited him in the hospital that he planned to go into the cave for just an hour and go home", Aikan said.
The Thai boys who were rescued from a flooded cave have spoken for the first time after their ordeal.
Four days later, a former member of the Royal Thai Navy, Saman Gunan, 38, died in the cave after losing consciousness underwater during an overnight operation delivering extra air tanks.
Public Health Minister Piyasakol Sakolsattayatorn said all 13 are set to leave the hospital on Thursday and they will need to be closely monitored for physical and psychological effects from their traumatic experience.
In the video, filmed on Friday, the boys give short statements.
Sompong Jaiwong, nicknamed Pong, added: "Thank you everyone from around the globe for helping us".
The boys and their 25-year-old coach were trapped after the Tham Luang cave complex was flooded.