I'm hoping to be living in Canada for a year shortly. I have a slight rivalry with friends about travelling north. My record is Murmansk, but it's about to be beaten by someone who is going to Tromsø, Norway (@Stuart). What's the furtherest north you can fly into? I'm assuming something like Svalbard (ironically with flights from Tromsø and Murmansk), but wondering if something can beat that?
Wikipedia has a very cool list for such kind of questions. It is called the List of northernmost items.
As you can see there, there are two possible candidates:
Airport, permanent without scheduled flights: Alert Airport, Nunavut, Canada 82°31′04″N 062°16′50″W
Airport, permanent with scheduled flights: Svalbard Longyear Airport, Svalbard, Norway 78°14′46″N 15°27′56″E
Now it gets difficult. You're asking for a commercial airport. The one in Nunavut is located in the northernmost permanent settlement in the world. So I think it is a clear win. The problem is, there is only twice a year a military flight to supply this settlement with goods. But it seems that you can get a trip with this plane.
If you think a commercial airport is only an airport with scheduled flights, your assumption Svalbard is correct.
According to wikipedia the northern most permanent airport with a regular schedule is indeed Svalbard (78°14′46″N 15°27′56″E).
I imagine there are possibly some further north in Canada but they may not have commercial flights.