If you coordinate a day trip on Saturdays, there is fare free bus service on the island. You can go over as a walk on and skip the long lines and walk ins/passengers only pay going one way. !
They load passengers usually last when boarding the ferry so make sure you are at the dock at least 5min before scheduled departure time of that particular sailing xx
If you travel frequently make sure to get a pass. It has 10(20 for cars) tickets on it and are much cheaper. They expire about every 4 months. $5.60 vs $7 for cars and $3.28 vs $4.10 for walkons. :)
If you have an iPad or iPhone you may want to check out NW Ferry in the app store for the latest schedules, fares, alerts & terminal cameras. Read more