Seattle Friday Harbor Ferry
In fact the Seattle Friday Harbor Ferry is just a myth... the Washington State ferry system does not offer ferry service from Seattle to Friday Harbor or from Friday Harbor to Seattle. However a private passenger ferry service - information here (only people no cars) is available during the summer months.
You can find that company and others on our Friday Harbor Transportation info section. For other ways of getting to Friday Harbor and the San Juan Islands visit our getting to the San Juan Islands page.
You can also ask travel and transportation questions on www.NorthwestAnswers.com where it is certain to get a helpful response.