Times may vary according to the seasons, why give them the direct link of the operator who organizes these cruises (St. Peterline) where you can find the updated information itineraries of the Baltic ferries passing by St. Petersburg usually ships out on the night of Petersburgo and arrive at Helsinki (or Tallinn) in the morning. It is convenient, because you don't lose the day and night aboard is you can sleep comfortably in the cabin. The same for the return, the ferry leaves for the evening and arrives at Petersburgo in the morning. These ships can be used in two ways: as a cruiser, i.e. for the pleasure trip down in the cities that are the route scales, visiting them during the day and returning in the afternoon on the Board to continue the journey or as means of transportation to get from one point to another and stay there, in this case is not bought the entire journey, but a part of the route, in our case we prefer the second option. Our idea was to go from Petersburgo to Helsinki, down there, spend two days in Helsinki, staying at a hotel (this time we chose the Crowne Plaza which was very good and comfortable although a little farther from the center than the) centrally located hotels where we usually stay usually) and return to Petersburgo.