How to reach vancouver Island from vancouver?

Adaviel is correct. There are ferries from Tsawassen(Vancouver side) to Schwarz Bay(Victoria side).
There are also ferries from Horseshoe Bay(Vancouver side) to Departure Bay(Nanaimo side).
Cars are charged separately from driver and passenger(s). The driver is counted as a passenger.
If you do not wish to gamble on being able to get on without having to wait for the next ferry, you can make a reservation, which costs extra, but will guarantee a space on the ferry that you want to take.
To make a visit to the island worthwile, you should take the first ferry in the morning(around 7 am), which will get you into Victoria approximately 10 am.

The ferry leaves to Victoria every hour and takes 95 minutes. It leave to Nanaimo on 2 routes about every 2 hours and 1 take 95 minutes, the other 2 hours.

Waits can easily be a full sail wait. Best times to cross are Wednesdays and Saturdays. Worst times for traffic are Long Weekends, Thursdays, Fridays, and Sundays.

Tsawassen to Swartz Bay (Saanich), takes about 100 minutes, every 1 or 2 hours
Horseshoe Bay (West Vancouver) to Nanaimo, ditto
Tsawassen to Nanaimo (less frequent)

You can book. Regular fare is $50/car + $15/adult = $7/child

The website is comprehensive, has PDFs, mobile version, maps etc.

You can take a ferry from south of Vancouver to just north of Victoria (Tsawassan to Swartz Bay) or from just north of Vancouver to Nanaimo. (Horseshoe Bay to Departure Bay) go to the BC Ferries website for schedules/fares.

Amazon 17 has a good answer. If you catch the bus to downtown Victor you can walk anywhere you want, its all relatively close. For adventure there are boats at the marina offering whale watching tours and wild life viewing.

Book a reservation. Going in the middle of the week is the best time to ferry traffic.

BC Ferries travels from Tsawwassen to near Victoria, and from Horseshoe Bay (West Van) to Nanaimo.