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It was supposed to be a day trip - 12 young boys and their football coach exploring the rugged mountains of northern Thailand and the Tham Luang cave. But instead, they disappeared.

Tham Luang is a 10-kilometre long limestone cave system with deep recesses and narrow passageways. Most of the year, it's relatively dry. But when the monsoon comes, it quickly fills with water, making the caves impossible to enter. Or to leave.

Within 24 hours of the boys going missing, a search operation was under way. The boys' bikes and backpacks were found near the entrance to the cave. Distraught family members gathered.

With water levels rising, the Thai Navy's elite SEALS diving team joined the search. At the same time, agencies and volunteers began the mammoth task of pumping water from the cave and surrounding area.

Soon the search had escalated into a major military operation. But by day four, there was still no sign that the boys were alive.

The Thai authorities called for international help. As some of the world's best cave divers gathered at the site, they soon realised the daunting task that lay ahead. They had to negotiate rising floodwaters, strong water currents, zero visibility and a labyrinth of tight cave passages that were kilometres long.

Were the boys alive? Where were they? If the divers found them, could they get them out?

On this episode of 101 East, the inside stories from one of the most extraordinary rescues of all time.

Source: Al Jazeera