Locating the exact coordinate of the abyss tunnel from one end to the other end was not an easy task. Even the experts from the world union spent a lot of time confirming the coordinates, and that's how they created the headquarters at this position.
Not to mention that this tunnel was not just a one-branch tunnel because there were many abyss gates spread all over the world.
The tunnel nearest to the abyss branched and the ones near the main world also had branches.
These branches might look small and the distance between branches were not wide, but the concept of space could not be easily seen like the usual thing.
The tunnel at the other end of the abyss had branches because the abyss was divided into several sections, and each section had one gate.
