It's common in Stockholm to take an overnight ferry trip back and forth between Helsinki Finland, Tallinn Estonia, or Riga Latvia. You can easily travel overnight in a cabin, spend the day in another town, and return back home in your same cabin. The ferries are more like small cruise ships heading to a single destination. They have restaurants, duty free shops, a dance show, a band, and a karaoke bar. Watching late night karaoke of predominately Finnish songs was definitely a new experience. The Silja Symphony ferry to Helsinki is one of the nicer ones with an inside promenade for the shops and restaurants. It was recently remodeled so it was particularly nice for one of these ferries.