huge fish that are not hostile would be pretty cool.

As someone who lives in the north of Sweden, I hope that Skyrim models the climate up here so that the lakes, rivers and sea all freeze over in the applicable season. Then you could walk across them and indeed ice fish if desired. I also hope that you can fall through said ice during late autumn or early spring when it is thin, or use it as a trap against enemies. In addition I hope that unless its summer time, that swimming in cold water svcks your endurance away at a horrific rate, leading to drowning.

Oh and to return to the purpose of the thread, yes I'd like to see a full underwater ecosystem too. Not just water monsters.

do you think they'll return those sea creatures from Bloodmoon? I loved them, they were cute..

It'd be pretty cool

More than likely. I can't see BGS leaving lakes and rivers uninteresting, lacking detail, and overall pointless. With Oblivion, I like to believe it was a lack of time and honestly Oblivion was miles ahead of Morrowind anyways graphically. With Skyrim though, subtleties like this should be expected for the most part.

I have to go with yes, because they way i see it the more content in this game the better so the more the merrier! The only reason i would say no is because i don't like going underwater in video games it gives me the creeps, does anyone else get freaked out about being underwater in video games? I think it started with the water castle in super mario 64 :/

But anyways my final verdict is yes because being creeped about something is no way to ruin possible content for everybody else am i right?

Bring on the sea monsters! i'll get a more emotional feeling when playing this game.

You only need to look as far back as Morrowind to see good examples of the very thing you are talking about. Underwater caves, pearl diving, slaughterfish, dreugh, shipwrecks and even temples littered the coast.