The fastest way would be to take either Helijet or Harbour air but this will be more expensive than land and ferry but before i go any further are you wanting just to see Victoria for one day and return the same day or were you planning to spend overnight - too attempt to do it in one day isn't realistic - from downtown Vancouver to downtown Victoria by bus and ferry is about 3 1/2 hours each way and if you don't clear the ship until 10AM doesn't leave you much time - if you are in a larger group you could rent a car/van but the ferries in the summer are very busy and often have one or two sailing waits although it is possible to reserve a spot for $15CDN - the ferry fare is about $40.00 CDN for car and driver and $9.00CDN each passenger each way.
Hope this get you started
Any more questions i will be glad to attempt to answer
Dennis