This place is an absolute blast! I planned a trip here for about 250 University of Toronto students for our Orientation Week and it was wonderful. Getting down the aquarium was easy enough as it's a quick 5 minute walk from Union Station and is very hard to miss once you turn the corner. If you are thinking about heading here with a big group, get in touch with them through the website - they are very accommodating and easy to work with.
We went down on a Friday night and it was lovely. Not only did we get to see Sharks after Dark and get the discount price on tickets, but also we got to enjoy live jazz music playing and echoing throughout the whole aquarium. The lit up signs at all the fish stations added to the whole experience so as you can imagine, there wasn't one student who didn't enjoy the experience.
The highlight of the exhibit was definitely the jellyfish section. Absolutely beautiful and breathtaking.