In Morrwind we got some real amazing new water for that time, but in Oblivion I wasn't that impressed by it.
When I think about Skyrim and its coast I imagine a rough and wild sea with big waves crashing on cliffs.
Found a video demonstration about some really cool water physics
http://www.youtube.com/watch?v=1JrM4ujLY_A
And Crysis had some amazing water effects, too and it's now more than 3 years old
Ocean
http://www.youtube.com/watch?v=2LnoD5R_VMM
Lake+Rivers
http://www.youtube.com/watch?v=X-d6tT34A3A&feature=related
Imagine those water effects in Skyrim, with some blizzards and so on, damn, I really want that