I'm just hoping to God it's not underwater like that uber-disaster Trials of Atlantis exp-pack for Dark Age of Camelot.

You're not looking forward to an entire "Deep Ocean, Vast Sea" expansion?

"OMG the murlocs are swimming through the walls!"

@Aggrajag

Swimming mounts and a turtle mount that I assume works under the water (not just surface otherwise what's the point?)... Either this is just a novelty item that can get you to islands just off the coast a little quicker, or its experimentation to gather data required for larger scale deployment of water based mounts for some nefarious underwater activities that might be planned for the future. Until I know the only reason I currenlty have to desire the turtle is to add one more to get my total closer to 100!

Anyway, I don't know about the next expansion, but I'm hoping, since Wrath is concerning itself a lot with the activities of the Titans, that Uldum becomes an instance/raid in another patch. I'd love more reasons to keep visiting the classic zones and see how those little hints of lore from vanilla wow play out now that we've uncovere some larger plots. I'd say the same for the "hidden" Eranikus quests (since we've been dealing with dragons a lot in Wrath too), but since I binned my Chained Essence of Eranikus trinket before I found them, I'm not so keen on having a questline I can't complete be expanded :-P

I'm not ruling out that land might be 'raised' from the depths of the maelstrom, or we enter a little 'bubble', as it were.

The idea of submersive dungeons, raids, even the majority of quests, just sounds horribly clunky, with or without water mounts.

I think the water levels are my least favorite in most of the games I've played in my life. An entirely underwater xpac sounds like fail waiting to happen.

Of course, I could be wrong. Blizzard does a really good job overall with everything they do. Maybe they'll pull it off and truly WoW me (u c wut i did thar?) with their sub-aquatic adventures.

MMOs were not meant to be played in 3 dimensions. Sure traveling on a flying mount is great but you don't have to worry about aggro or fighting.

Underwater fighting killed DAoC. It was probably a litter worse in that game because all melee dps was position based but in any case it is no fun at all.

Just imagine and entire expansion that is like the occulous but the mobs move around and you have to worry about running out of air and you move at half speed. Wheeee fun.

I once had a really cool dream where blizzard implemented a Maelstrom expansion that focused mainly on adding islands to the game.
Added cities included Undermine as a neutral city, an ancient troll temple to finally give the Darkspear Tribe a capitol, and Metrognome, a flying city belonging to the Gnomregan Exiles, similar to Dalaran stationed to spy on their rivals in Undermine.
Many islands had high cliffs and cave layouts which increased what initially appeared to be very small surface area, while other islands like Undermine were rather large both in apparent size, and surface area. There was also an instance that involved a ship that gets knocked off course and ends up sailing through the Maelstrom, with different monsters attacking along the way. The actual Maelstrom was a "locked" area to be added in a later patch as a raid.
After this dream, I decided to take a break from WoW for a while.
My point is, there's alot of Azeroth at sea that isn't necessarily under-the-sea. Furthermore, if Blizzard does implement an underwater dungeon/raid, I think they would supply us with the means to move relatively freely through them either through buffs, or vehicles.
As to what the next expansion will be, I'm leaning more towards the Emerald Dream. The portals are already there, and there's some nice plot advancement for it with the Scythe of Elune making another appearance, the Emerald Dragon Shrine, and of course Vordrassil.
Lastly, I'd like to emphasize that this entire post is speculation.

Yeah, I think that the Emerald Dream/Nightmare would be pretty cool, but I hope hope hope that it won't be like the "taste" of it during that long questchain trying to save Bridenbrad... that kind of disappointed me. My ring was worth it I guess =P
I still think Maelstrom would be cool, but I didn't mean completely underwater, maybe we get to go to the island where the Goblins originated, etc. And maybe if they did choose Maelstrom, the dungeons could be kind of like SSC, where its a cavern underwater.