You're going to want a high-quality map. Even if you are bringing a GPS unit, bring a good map and a compass, too. You don't want to strand yourself if the batteries fail or the device gets stranded!
My favourite compass is the Silva Trekker, but there are lots of good quality compasses on the market. Key necessary features are a rotatable dial, a mirror with a sight, and a ruler. Do not cheap out on your compass! Cheap compasses will fail you. I bought my Silva once, and I'll probably be using it for the rest of my life.
Unfortunately my GPS isn't available on the market anymore, so I can't recommend one just yet! Make sure you can get good quality maps for your canoeing area and that it's not just for driving! My GPS is "dumb" and only works on user-set waypoints, it doesn't care about roads and highways and turns and all that. That's what you need!