The transfers that matter most here are the ones that cross water or cover distance: Victoria to Vancouver by coach (which includes the BC Ferries crossing from Swartz Bay to Tsawwassen), Victoria to Seattle on the Clipper fast ferry, and airport runs to Victoria International (YYJ) on the Saanich Peninsula or Nanaimo (YCD). Cruise passengers arriving at Nanaimo's port will find private transfers to Victoria listed here too.
Within Victoria itself you rarely need a transfer: downtown, the Inner Harbour, Fisherman's Wharf and the Ogden Point cruise terminal are all walkable or a short bus ride apart. It is the moment you want to be somewhere else on the island that a booked seat or a hired vehicle earns its keep.
Overland and camper rentals are listed here as well. They suit itineraries that go north of Nanaimo or out to the Pacific coast, where public transport is close to non-existent and the drives are long.