The requirements to enter Canada are: a certified birth certificate or a passport. If your passport is from a country from which Canada requires a visa--that might pose a problem.
The way to get around this is to fly into Alaska or take the Alaska Marine Highway (Ferry) from Bellingham, WA (just south of the Canadian Border). You could fly to Anchorage and take the ferry back. It's tempting to fly into Ketchikan and start out from there, but Alaska Airlines is the only air provider and the cost is around $700 RT per person unless you can find a web special. Try after 5 p.m. on Tuesday evenings for those.
A flight into Juneau is an acceptable alternative.
Smaller ships cost lots more - fewer passengers to share the expenses. Cruise West is a very reputable line - but is 3 times the cost of a trip on Holland America, Princess, Celebrity, Royal Carribean, Carnival, Norwegian or Radisson lines.
You do have lots of choices to choose from. My dream trip is to take the Alaska Marine Highway system from Bellingham, get a stateroom (it's 2 nights/3 days from Bellingham to Ketchikan - stay in local B & B's and either rent a car in each town/or hire a cab to provide a narration of what it is I'm seeing. The next town is Wrangel - 6 hours away by ferry so no stateroom is needed. I'd continue on - with the possibility of taking a bus trip from Skagway or Haines in to the interior (passport or birth certificate required in Canada) or continue up the Alaska coast to Anchorage. You can take a train or bus to Fairbanks if you want to see some of the interior.
I would eventually fly back to the US.
