It's located above the original entrance and is 9m long and 2m wide. Source: ScanPyramids Video Report Nature (2 March 2023): Precise characterization of a corridor-shaped structure in Khufu’s Pyramid by observation of cosmic-ray muons NDT&E International (2 March 2023): Localization and shape determination of a hidden corridor in the Great Pyramid of Giza using non-destructive testing