Boys from the under-16 soccer team trapped inside Tham Luang cave covered in hypothermia blankets react to the camera in Chiang Rai, Thailand, in this still image taken from a July 3, 2018 video by Thai Navy Seal.

Rescue teams thrashed through dense forest hundreds of meters above a cave complex on Friday, searching for an alternative way to extract 12 boys and their soccer coach trapped inside for nearly two weeks.

Their work above the Tham Luang cave near Thailand’s northern border with Myanmar took on added urgency as forecasts for rain threatened a plan to bring the boys back through cramped, water-logged passageways to the cave entrance.

“We want to find the way down. I believe we are close,” Thanes Weerasiri, president of the Engineering Institute of Thailand, told Reuters at a makeshift camp for volunteers and media near the cave.

Helicopters buzzed overhead before flying to the dense blanket of green hills above the cave to help look for an alternate extraction route.

Rescue efforts since British divers found the team on Monday have focused on draining the flooded cave and teaching the boys – some of whom are as young as 11 and not competent swimmers – to attempt dives that would challenge expert cavers.