Spoiler:
The innkeeper is about his usual morning routine behind the bar. Your question causes him to straighten his posture "Underport? You serious boy?" The older man says, look of deep concern hewn upon his features, "That's a loft of all types of villainous sorts."
With a sigh, he contiues, "If you are serious, then you may be in luck. I've made my travels to many places in this wide world. Had it been someone else, they would have stared at you with a blank expression. Underport is beneath the port of Agronon. First travel East upon the main road. You will travel for several miles until you encounter a massive cemetery. Take the main road to the center of the place. There you will find a crossroads. Head south from there and you will find yourself at the port of Agronon. For the right price, you can buy the information to gain access to the underport. Be wary, however, someone will just as quickly put a knife in your back and leave you for dead as tell you the location of the secret bandit port."
He moves in a little closer, "While in that graveyard, never leave the road. You hear me boy? There are rumors of vile magics at work and it's best to not be mixed up in such things. Necromancy has never been a positive arcane rite for the living."
With a sigh, he contiues, "If you are serious, then you may be in luck. I've made my travels to many places in this wide world. Had it been someone else, they would have stared at you with a blank expression. Underport is beneath the port of Agronon. First travel East upon the main road. You will travel for several miles until you encounter a massive cemetery. Take the main road to the center of the place. There you will find a crossroads. Head south from there and you will find yourself at the port of Agronon. For the right price, you can buy the information to gain access to the underport. Be wary, however, someone will just as quickly put a knife in your back and leave you for dead as tell you the location of the secret bandit port."
He moves in a little closer, "While in that graveyard, never leave the road. You hear me boy? There are rumors of vile magics at work and it's best to not be mixed up in such things. Necromancy has never been a positive arcane rite for the living."