The Canals
From WoWWiki
The Canals of Stormwind are a series of waterways that wind their way through the city, separating each of its various districts. While the Canals is mostly used for thoroughfare, it does house a few shops overlooking the marble pathways and docks, and it is a popular area for fishermen to spend time hauling small catches. The Canals also house the infamous Stockade.
The Canals are accessible from every single district in Stormwind, and is indeed quite hard to not cross at one point while staying in Stormwind.
Adventurers should be wary of falling in the canals, as there have been reports of a giant albino crocolisk roaming them.
