Going to Fire Island would not be nearly as much fun without the ferry. While you wait you will see rental people with large quantities of provisions to last their stay as well as happy day trippers, couples and families alike. The trip itself is gorgeous and relaxing. It is like going on vacation (which is pretty much the case no matter how short your stay). Do use sunscreen and be prepared for a parking nightmare unless you go on an unpopular day or get there very, very early.