I can recommend Poland: Warsaw and Krakow are very beautiful cities. Budapest is also nice, if you're looking for a city with a kosmopolitan vibe.

Mwoaster: Thank you! I've been told by friends that if I loved Berlin Budapest would another city I would really enjoy. I've also looked at doing Krakow and Warsaw, plus maybe a countryside area in between the two or around them for a night or two can you reccommend any?
@michx: can't help you with that I'm afraid. :)
In Germany I can recommend Weimar, a nice little city. Don't know if you can fit this in though.

I've actually been pretty close to there before, I used to live in Hanover which was roughly 3 hours by car and went there for a day trip
Longislandbob- Thanks a bunch, I'm looking at maybe doing it in Queensland
You are welcome Michelle.
Around here, SCUBA divers do a lot of training at Dutch Springs, near Bethlehem PA (about 8 hours due south of Ottawa). It's seasonal, but they have a pretty long season.
http://dutchsprings.com/scuba.html
http://dutchsprings.com/rates.html#month
If you don't go on a summer weekend, hotel rates are also quite affordable. (There is a Disney world styled amusement park and water park nearby that drives up rates during summer weekends.)
Dutch Springs has an on-site campground if you want to save even more money.
Here on Long Island NY we have a LOT of diving opportunities (wreck diving, clamming, and spear fishing), and the diving community is rather large, but hotel expenses etc. tend to be quite high so we have never really developed into a tourist destination for SCUBA. We are more like a weekend destination for NY City residents.
~Bob