I think that sea battles were going to be just autoresolve type to be able to focus in land ones (or something like that was said long time ago). Maybe, if we are good, Stardock would consider to add "real" sea battles in an expansion (making the necessary changes to make it work... if it can work at all in those conditions) or maybe it's moddable and some modders can add it. Considering what we currently know about how battle works, just now we can only guess.

I want underwater cities.

Yes, I'm hoping the Developers can give a quick comment on what's planned for the water terrain(s).  (Shallow waters, Deep waters, Icy waters, etc., ) 

I completely agree with your first paragraph, NTJedi. I'll be disappointed if water doesn't allow for at least that much.

On the topic of underwater cities, I agree they'd be cool but they wouldn't really make sense. The two playable races are humans and human-derivative Fallen, neither of which live or even can live under water... I guess you could make it work through magic but it seems a little excessive to me. On the other hand I'd love it if they design waters keeping underwater cities in mind, so that they can be added in later on by an expansion or mods. 

I actually really hope they don't do this (and as of Stardock's last comment on this matter, water battles will be auto-resolved). The reason is, if I have an army of 5000 soldiers, some of whom may even be mounted, they really aren't all going to fit onto the decks of two ships. Not to mention I wouldn't want to be riding a horse on a ship (bears are more stable though, so that wouldn't be so bad ).

I'm not too bummed that they aren't planning on having player-controlled naval combat, but I would definitely be excited if they reverse that decision or if they add it in for an expansion.

I think the best way to do player-controlled naval combat would be to have the players control their individual ships. Flying and swimming units would also be able to participate directly in combat. Maybe ranged units could, too. There could be multiple ways of defeating enemy ships:

1) You could immobilize ships with sails by doing enough damage (think taking out the mast)
2) You could physically destroy it (most easily accomplished via warships, magic and large powerful creatures) 
3) You could disable it by killing its crew. Ranged, flying and some sea creatures, as well as magic and onboard armaments would help here. Also, it could be possible to simulate boarding other ships, in which case melee units would also contribute.

In the case of melee and ranged units contributing to such naval battles I think it'd be best if, rather than acting is individual units they simply contribute to ranged and boarding strength stats, abstracting away that level of detail for the sake of practicality.

Nonetheless, I could easily see a system like this becoming very unwieldy once fleets get big enough. For one, you'd have to choose how to distribute your forces across your fleet, which could be very tiresome. Secondly, if you control individual ships, well, things would get chaotic once fleet sizes start heading upwards of a couple dozen ships. So basically, I'm not holding my breath for naval combat. 

With that, i'm more than happy.

And if my channeler will be able to shatter the world... why not be able to develop magics that allow for underwater settlements/cities/fortresses/dungeons/theme-parks...?

Well it depends. The first complication depends on how water is implemented. Whether the city shows up on top of the water or below it is something that would need to be taken into account; and to be underwater requires that there actually be editable terrain under the water. I know that this has been problematic in some games in the past.

Secondly, we've been told that cities will be affected by local landscape - which means that underwater terrain would need to be assigned sensible properties for cities. If done well this would mean making a variety of underwater terrain types; if done poorly all underwater tiles would be the same. Either way it's something that needs to be taken into account when designing the game.

And the third thing is accessibility. The plan is for there to be a comprehensive caravan system connecting a players' cities. How would that work with underwater cities? A regular caravan isn't going to be able to just waltz into the ocean under the waves. Not to mention getting anything at all too and from the city, not just caravans. 

All of these things need to be considered for underwater cities (and floating cities), and they can all be done - obviously the earlier the easier. And I personally think it would be a Very Good Idea for Stardock to make sure that all of these complications (and others that I've probably missed) are dealt with so that even if Stardock themselves don't implement the features, modders can. 

well I'd imagine the sea floor would be on the same 'map' as the underground (if such a thing exists) then access would be through coasts or something, as well as through special cavern holes from the underground (think something like the air pockets in Ecco the dolphin, or the save rooms in the underwater levels in recent castlevanias (order of Ecclesia for example)

Alternativly they could just be exactly like land tiles in every way, except only boats and aquatic units can actually be 'in them'.   Maybe a little loading dock on the surface of the ocean, and the rest can be seen through the surface waves under the bed.

Well to even get underwater cities you'd need something like magic mass-water breathing, the ability to create underwater domes/air pockets, or just plain aquatic/amphibious creatures.   So that being said, a gungan (sorry for using starwars) caravan COULD go to an underwater city.  At the same time, a road with 'underwater travel' cast on it might be able to let normal air breathers pass underwater along it.   lastly, a global spell like "ocean air" that lets all creatures breath water like air, then any caravan could do it as well.

I'm not worried about the AI.  Frogboy said that the AI is going to be able to adjust to mods and anything, and I believe it will have no problem.

fair enough.  but that being said, there you go!   your caravans are always going to have water-trade routes.  So the 'caravan' will just be a boat the moment it hits water.   And/or you could just build an underwater tunnel of some sort.  (glass pipe Bioshock style would work).   Sounds like normal caravans can easily make it to underwater (or floating?) cities

I would like to see independent underwater villages, towns or cities used by amphibian or aquatic beings.  The same as independent villages, towns or cities on the land it should be possible to trade, ally or attack these locations... naturally since they are underwater either breathe underwater spells or special water_type beings/creatures would be needed for traveling to these locations.

I like the idea of underwater domes, but this should be one of the higher research technologies since an underwater location usually provides access to several land locations.  An underwater location using a dome would also need special types of defenses against anything which may threaten the dome... such as a giant sea serpent or underwater ballista.

Also  I would hope eventually Elemental:WoM would have two types of battles for the  seas, lakes and oceans.  The first would be a battlefield for the surface of the waters... this would usually be between ships, but may include water_type creatures.  The second type of battlefield would be underwater which is between water_type beings/creatures or those who can magically breathe underwater.