Flights:

Comox, BC is the closest airport to Campbell River, that is unless you're brave enough to build a plane yourself and fly it straight to Campbell River...

Victoria, BC is also a option, but keep in mind its a 3hr drive to Campbell River from there.

Drivers:

Don't like to fly? Want to take the scenic route? Keep in mind you will be taking ferries. Also strongly recommended to book the ferry in advance as its a necessity now. Therefore your schedule shall bear that in mind...if you're driving you're most likely going to see a bear, and I will be jealous.