Sandy Point Park sounds really inviting; the Polar Bear Plunge.... er, not so much.
I did jump off the bridge over the Yellowknife River twice in one day as a youn'un. Once w/ dog, once w/out. Ruff, the dog in question, preferred the jump w/out his furry self, no doubt. We both set speed records getting to the bank. I'll never forget the look he gave me!!
That river runs over a lot of permafrost before it gets to that bridge. There was significant shrinkage.