You've conquered the Caves of Calamity, the Dungeon of Moderate Annoyance, and even the Tomb of Creepiness. Now that extremely well-connected old man with the eyepatch tells you that there's an ancient underwater city nearby. He even gives you a bunch of magical rings that will let you breathe underwater. Time to kill some scaly, fishy things in this Journeyman Level Qerth adventure.