The Sewers (Act 3) Farming Guide - Diablo 2
How to Reach: Upper Kurast (WP) or Kurast Bazaar (WP) > The Sewers Level 1
Zone Level: Nightmare: 52/53 -- Hell: 84/85
Golden Chest: Yes (On Levels 1 and 2)
Boss/Champ Packs: 4 - 8 (Level 1)
Hell Immunities: Cold (Gloombat), Lightning (Horror), Magic (Horadrim Ancient), Poison (Feeder, Preserved Dead, Undead Soul Killer, Slime Prince [Lvl 2])
The Sewers in Act 3 are a level 84 (Level 1) and 85 (Level 2) zone making them decent places to farm if you don't mind the layout of the place. Most level 85 zone lists don't mention this place since only a single Champ/Boss pack can spawn on the second floor and finding the second floor is a bit of a hassal. The upside is there is always a Golden Chest on the second floor for you as a complimentary prize.
Most people don't farm this zone solely because the second floor is a level 85 zone though; they do so because the first floor is very large, easy to kite on and is a level 84 zone. There are only a small handful of items in the game that can only be obtained in level 85 zones, farming a level 84 zone will still get you the majority of the best loot in the game. For more information about how this all works check out my Magic Find Guide, that goes into much more detail about Treasure Class and what it all means.
If you're going to farm in this location I strongly recommend you do so with a character that has Teleport, otherwise you'll waste too much time trying to navigate the maze of walk ways and dead ends. The zone itself is massive and is connected to both the Kurast Bazaar as well as Upper Kurast.
Teleport also makes it significantly easier to kite enemies around in this zone, especially if you have an ability that can slow, like Blizzard Sorceress' do. Use the rivers everywhere to your advantage, most enemies can't Teleport or fly across them which makes it very easy to exploit their poor pathing.
For the most part this zone is large enough for you to skip any monster you don't feel like dealing with, if you encounter a pack with immunities that you can't handle it's unlikely it'll follow you very far due to how the zone is designed the enemy pathing here is extremely easy to take advantage of. That's one of the main perks of farming here aside from the high Area Level.
On The Sewers Level 1 you will typically find anywhere from 4 to 8 Boss/Champ Packs and on Level 2 you'll find 0 to 2. There will be a Golden Chest on both levels of The Sewers but only the one on Level 1 is an 'actual' Golden Chest. The one on Level 2 contains a piece of Khalim which is used in the Act 3 Quest 3: Khalim's Will.
Despite the Golden Chest not being a Super Chest on Level 2, you'll find (usually) at least two regular chests that are. The Golden Chest always spawns at the northern most end of the room but the southern end and southeastern end will both have normal chests that are considered Super Chests.