The tunnel was about 3 kilometers long.
Egyptian security sources said, "The tunnel is intended for infiltration of terrorist elements from the Gaza Strip to plant improvised explosive devices on the Egyptian side and to support terrorist elements supporting the ISIS organization in Sinai and transport weapons and explosives."
Egypt says it seized ammunition and explosives inside the tunnel.
Egypt has claimed that Gaza elements, almost certainly with Hamas' knowledge, are supporting ISIS attacks in the Sinai. Hamas strenuously denies any involvement, and it would be a fairly stupid thing for Hamas to do. So it is hard to know how much to believe the Egyptians, although if they recovered weapons in the tunnel, it it better to destroy it no matter whether they were being smuggled into Gaza or out of Gaza.