When traveling long distances in the nether, the player's location in the nether is passed directly to the overworld. For example, you are in the ubication 0 50 8000 in the nether and you want to return to the overworld, you make a portal to go to the overworld, but instead of being multiplied by 8 the coordinates, it just teleports you to 0 50 8000 in the overworld.