MAE SAI, Thailand — Improbably enough, most of the escapes went flawlessly.

But on trip No. 11, to save one of the last soccer teammates stuck for 18 days deep inside the cave, something went dangerously wrong.

Rescuers inside an underground chamber felt a tug on the rope — the sign that one of the 12 boys or their coach would soon emerge from the flooded tunnels.

“Fish on,” the rescuers signaled, recalled Maj. Charles Hodges of the United States Air Force, mission commander for the American team on site.

Fifteen minutes went by. Then 60. Then 90.

As the rescuers waited anxiously, a diver navigating the 11th teammate through the underwater maze lost hold of the guide rope. With visibility near zero, he couldn’t find the line again. Slowly, he backtracked, going deeper into the cave to search for the rope, before the rescue could resume.