When making your plans to visit places in or near the San Juan Islands you will invariably end up dealing with the Washington ferry system in one way or another. Boaters sometimes need to send someone home or meet an arrival. Simply avoiding a Friday Harbor traffic jam out on the water or on land is avoidable if you know when and where ferry's hang out.
If you think about it you realize that commuters and vacationers share the same system. People are heading to work and coming home mixed in with tourists. According to WSDOT the busiest ferry travel times are Thursday and Friday evenings westbound and Sunday afternoons eastbound. In the San Juan's, peak travel times from Anacortes are Thursday and Friday afternoons and Saturday mornings. Peak travel times from the islands are all day Sunday and Monday mornings.
Armed with a little ferry knowledge it is easy to work out a vacation schedule that minimizes or complements just about all visitor plans.
Follow this link to the WSDOT ferry schedule page.