Besides the ancient and magnificent hoists and locks through the south sea-caves and the subsequent tolls levied by the Keepers, there are others ways one can arrive to the Port of Shadow—if such a place even exists that is; but it is also said that Skullport is Waterdeep’s worst kept secret. Nevertheless, Underdark port and its secrets exist and operates outside the knowledge and purview of many Waterhavians.
One such passage located in a well in the basement level of the Blue Mermaid tavern in the Dock Ward, a saloon targeted by the Cult of the Dragon during the first dragon attack. The course leads to the Underhalls, but was blocked off by the Knights of the Firelance after it was discovered that a band of slavers was using it to transport captives to Skullport.
Unknown to the Gunslingers, in no time the Shadow Thieves reopened the passage and had a permanent illusion of the wall emplaced to fool the unwary. The well shaft drops down more than 75 feet to a dank, fetid stone floor that faces the illusory brick wall. The tunnel behind the illusion is more a steep, slippery stairwell of well-worn rock than a passageway. It winds for a long distance through rank passages and poorly lit areas dripping with slimes, molds, and fungus.
At least once every mile along its length a pair of doors flank the passageway: One is a lockable cell door into an empty 40-foot square room for slaves, and the opposite one is a guard room for the slavers, complete with two sets of bunks and small chests for holding spare weapons and gear.
The long ways from the Blue Mermaid can be traveled in about eight hours if one moves at breakneck speed and is not either transporting slaves or attempting to move quietly or carefully. On average, traversing this passage nonstop from the Blue Mermaid to its exit takes 12-16 hours. It exits onto an opening on the western wall of the Upper Trade Lanes, opening on to a catwalk over a warehouse.
Another means of access leads to Skullport from the dungeons of Castle Waterdeep. It winds like a massive corkscrew into Undermountain, bypassing the underhalls and going straight to the The Threads. This route is shorter but due to its location under the castle, it has been blocked off as well by the Knights of the Firelance. This winding passage has a final descent down a well shaft of 120 feet, complete with an iron rung ladders set into the side of the shaft. The shaft apparently ends in the open air, stopping in the ceiling of the Heart directly south of The Threads. An iron spiral staircase actually connects with the well shaft, though the stairs have been rendered invisible to normal sight and infravision.