Cataclysm: Vashj'ir

Vashj'ir is Cataclysm's (and WoW's first) underwater zone. This change of venue provides an experience that's quite unique from the other zones. The other zones, especially those introduced in Cataclysm, are all very well designed. The new zones follow solid story lines, interesting quests, and a feeling of real progression in the world with use of phasing.

But running around underwater is something else altogether. The first major challenge is coming to terms with the 3-dimensionality of it. Now, you're just looking around you on a 2D plane for enemies and quest objects, now you're coping with enemies and objectives above and below you.

It's an interesting format, and it creates a new sense of immersion. The zone also lacks a lot of the single-toned lack of variation that other zones often have. You have kelp forests, deep abysses, high elf/naga ruins, and you even get to go running around a giant squid.

One of the quest lines I found the most interesting was one that sent you back in time to play as a naga Battlemaiden. You uncover stirring intrigue, deep mysteries, and epic battles. It's so vastly removed from anything else you encounter in the game.

While I was incredibly happy with the other zones as well (Uldum is probably my favorite) but the uniqueness and innovation present in Vashj'ir (and awesome sea horse mounts) makes it more than worth going through, and even more than once.