There is no bridge. Everyone arrives by water or by air, and the choice decides where you start your island trip, which matters more here than almost anywhere else, because the island is 450 kilometres long and the places people come for are at opposite ends of it.
The short version: BC Ferries is the way to bring a car; the floatplane and helicopter are the way to reach downtown Victoria fastest from downtown Vancouver; the Clipper is the way from Seattle without a vehicle; and flying into Comox or Tofino skips the long drive north or west entirely.
The three main BC Ferries crossings
BC Ferries runs three car-carrying routes from the Vancouver side. Tsawwassen to Swartz Bay lands you about half an hour north of downtown Victoria and is the route for the south island. Horseshoe Bay to Departure Bay lands in central Nanaimo, the natural start for Tofino, Parksville and everything north. Tsawwassen to Duke Point also reaches Nanaimo, slightly south of town, and is often the quieter crossing.
Each crossing is roughly an hour and a half to two hours on the water, plus check-in time. Vehicle reservations are sold for all three routes and are worth having on summer weekends and holiday Fridays, when unreserved cars can wait through more than one sailing. Foot passengers rarely need one. The terminals on the mainland are a long way from downtown Vancouver, so add an hour of city driving or the BC Ferries Connector coach to any plan.
Downtown to downtown by air
Harbour Air floatplanes leave from Coal Harbour beside the Vancouver Convention Centre and land in Victoria's Inner Harbour, a few minutes' walk from the Empress. Helijet does the same trip by helicopter from the heliport beside Canada Place to Ogden Point. Both are about 35 minutes gate to gate and are the only way to make the crossing without losing half a day, which is why they suit a short Victoria stay or a whale-watching day that starts in Vancouver.
The catch is weight and weather. Baggage limits are tight, fog cancels floatplanes on winter mornings, and neither takes a car. Book the earliest flight if you have a tour to catch.
From the United States
The Victoria Clipper is a passenger-only fast ferry from Pier 69 in Seattle straight to the Inner Harbour, and it is the reason so many Seattle day trips to Victoria exist. The MV Coho carries vehicles from Port Angeles, Washington, across the Strait of Juan de Fuca, also into the Inner Harbour, which makes it the natural route for anyone touring the Olympic Peninsula first. Both are international crossings: bring a passport and expect border formalities at each end. Schedules thin out in winter, so check the sailing days before you commit to a hotel.
Flying in
Victoria International (YYJ) is near Sidney, about 25 minutes north of downtown, and has the most flights. Nanaimo (YCD) is small and convenient for the centre of the island. Comox (YQQ) is the airport for Campbell River, Mount Washington and the road north, and saves the drive from Victoria entirely. Tofino-Long Beach (YAZ) takes short flights from Vancouver's South Terminal and drops you between Tofino and Ucluelet, which is the fastest way to a storm-watching weekend. Port Hardy (YZT) serves the far north. Car rental exists at all of them but is limited at the small ones; reserve before you fly.