The tunnel is an opening found in the Miscellania and Etceteria Dungeon. The tunnel requires an Agility level of 40 to pass through, granting 1 experience when successfully passing through. The player can boost up to 40 to pass through the tunnel, however if they drop below 40 they can always go back through as the requirement is for going deeper into the dungeon (this action gives 0 experience).
40