Just a short distance down the 'main' tunnel that the lone ledge-survivor had been running, there is another tunnel branch traveling almost parallel to the 'main' one. While the main tunnel is nearly 20 feet across, the side branch to the ledge and the new branch are barely 10 feet across. The main passage continues south, appearing to widen very gradually. Where it goes is obscured by distance and darkness.
Everyone roll a spot check.