By plane
The Victoria airport has flights from various locations in Canada. There are also flights from Vancouver to many of the towns and cities on the island. Floatplane facilities located both in the Victoria and Maple Bay.
Floatplanes operated by Harbour Air,Salt Spring Air (http://www.saltspringair....) fly frequently from-to downtown Vancouver, YVR and other destinations including the scenic Gulf Islands. Some of these float plane operators will also do tours of the city and nearby attractions starting at about $80-100 per person... a great way to see the island.
Direct flights to Comox on the east central coast of Vancouver Island are available from Calgary or Edmonton on Westjet. (http://www.westjet.ca) . There is also a connection to Comox from Vancouver on Pacific Coastal airline.
By ship
The most common way to get to Vancouver Island is by BC Ferries (http://www.bcferries.com/). There is regular ferry service from Tsawwassen near Vancouver to Swartz Bay Near Victoria, Tsawwassen to Duke Point near Nanaimo and Horseshoe Bay Near Vancouver to Departure Bay in Nanaimo. These ferries generally run about every two hours with more frequent service on some of the routes in the summer.
There is a ferry service that runs from Powell River to Comox, and Port Hardy to Prince Rupert.