The road from Hellfire leads to the Zangarmarsh, a lush, alien mushroom forest in contrast to the barren red of the Peninsula. It looks a lot like a cross between Morrowind and Myst.
The local Alliance outpost, Telredor, is built on top of a giant mushroom. Sadly, although it implies that they've carved into it, you can't really go inside. I believe the name is a reference to Morrowind - Telvanni plus Redoran. House Telvanni was pretty cool. They gave me my own mushroom palace. According to WoWWiki, some people have difficulty not dying while taking the elevator up? How do these people manage not to die in real life?
The wildlife here is pretty alien. Fen striders resemble jellyfish crossed with Martian war machines. Fen striders are awesome and I wish they made them as mounts.
Also: sporebats! Sporebats are cool too.
There's also a race of mushroom-people, who live in a town called Sporeggar. They're pretty nice to you, also they accept mushrooms as money.
They grow out of pods, apparently. And the giants that live there are mean to them. Basically everyone picks on the sporelings. Poor sporelings.
Actually, there's quite a few things going wrong in Zangarmarsh. For some reason, ogres are chopping down mushrooms. I don't think it ever explains why they're doing this. It's probably just because they're jerks.
Also, the naga have migrated here and set up big pumps in every lake, draining the water for their own insidious purposes. Again: why? Why do the Naga need so much water? Just to be jerks.
The northern lake has already been sucked dry. The lights on the mushrooms flicker in and out in a sickly kind of way.
All this water flows into the gigantic Coilfang Reservoir at the center of the big lake, which is one of the new dungeons. Again: why do they need to do this?
They built a massive drain at the center of the lake that sucks in a lot of water? I guess? And all the other pumps empty out here... Seriously. Why.
Who's that handsome girl on her handsome steed? It is me!
Next: Terokkar Forest.