Visit St. Petersburg by ferry without a visa
Thanks to the law that allows cruise ship passengers to visit St. Petersburg without visas, it is also possible to take the ferry from Helsinki or Tallinn and stay in St. Petersburg for up to 72 hours without a Russian visa.
The 72-hour visa-free regime is also extended to ferry passengers traveling from Helsinki or Tallinn on services run by St. Peter Line. Depending on the sailing schedule, you can then stay in St. Petersburg for 24 or 72 hours without obtaining a visa. Technically, this is also classified as a cruise, and to maintain the pretense you are obliged to book a city bus tour through St. Peter Line. This is in fact a shuttle that runs across Vasilevskiy Island to the city centre, and you can get off whenever you wish. Whereas regular cruise ship passengers are obliged to sleep on board unless they obtain a Russian Travel Visa, St. Peter Line passengers will need to book hotel or apartment accommodation for their stay.
Please note: This rule only applies to passengers on St. Peter Line ferries. If you plan to visit St. Petersburg from Helsinki by train or bus, you do need to get a Russian visa before departure.