This article is incomplete. Please feel free to edit this article to add missing information and complete it. Reason: full list of what items are available only if sewers are flooded
(Japanese: ヒウン下水道Hiun Sewers) is a location in south Unova. It is accessible via an entrance in Castelia City, on the pier near the Bridge Gate. When exploring for the first time, Hugh will join the player as a tag partner. Here the player meets Colress for the first time. Relic Path is accessible from here. There is also an exit to Castelia City's park with wild Pokémon, and when the sewers are flooded, to Castelia City's back alley. During autumn and winter, the sewers are dry, blocking some areas and removing the requirement of Surf to access others.
Once per day, a female Scientist in a room near the Doctor and male Scientist near Janitor with Marill and Cinccino attempting to turn poison into medicine will give the player an item created in their experiment. They can give out any one of these items on a daily basis.
colspan="2" style="background: #Template:City color light; color:#000000; border-top-left-radius: 5px; -moz-border-radius-topleft: 5px; -webkit-border-top-left-radius: 5px; -khtml-border-top-left-radius: 5px; -icab-border-top-left-radius: 5px; -o-border-top-left-radius: 5px;" | Item
class="roundybottom" style="background: #Template:City color light; color: #000000" colspan="14" | A colored background means that the Pokémon can be found in this location in the specified game. A white background with a colored letter means that the Pokémon cannot be found here.
Trainers
Even when partnered with Hugh, Trainers other than the Team Plasma Grunts are engaged only in Single Battles, without Hugh.
The Castelia Sewers makes an appearance in A Venipede Stampede!. Burgh, Ash and his friends observe a Venipede stuck in one of the pipes and the Venipede gets freed with their help. Notably, it appeared in the anime long before the area was accessible in the games.
