I live in Oz.
Unless you go to Ningaloo Reef on the West Coast at the appropriate time, or see a Minke whale (never done it in-water) on the East Coast again at the appropriate time, the closest "big animal" action you are likely to see is Reef Sharks, other sharks will undoubtedly see you but you are most unlikely to see them. The closest I've come to a Great White is finding a couple of their teeth once at a Reef near Forster (NSW and a top diving destination). I was there visiting with the Grey Nurses which, again, are a seasonal experience.
I shoot a DSLR for which I have 2 x Macro lenses, 2 x Wide Angles, 2 x conventional Zoom lenses and a Fisheye. Although I always take all of these away with me on diving trips it's the Fisheye and the Macro lenses that get the most use in fact the least-used lenses are probably the wide angle ones. I do point out that here I am talking about Oz only, things might be very different if overseas or if I am going to a Great White expedition in South Australia when my widest lens might (just) do.
But you're not going to do any of that on your first trip so I highly recommend to you the KISS (Keep It Simple and Straightforward more commonly seen as Keep It Simple, Stupid) principle. But, yes, the more you can practise with your new camera in Canada, the better off you will be here in Oz. That applies equally to your diving, don't put it off, do it now and the sooner the better. Then practise, practise, practise, then practise some more. Trust me when I say that, in SCUBA, practise doesn't make you perfect, nothing does that. It merely makes you that little bit more competent.