To get from Stockholm, Sweden, to Helsinki, Finland, and back, travelers have few transportation options due to geography. Each transportation mode has pros and cons, so let's find out which is the best choice for your travel between these two cities.
Stockholm to Helsinki by Air
Many direct flights between Stockholm and Helsinki are operated by Scandinavian Airlines (SAS) and Finnair. They're also usually the cheapest flights available between these two cities, starting at around $90 one way.
The flights from Stockholm to Helsinki and vice versa depart several times a day and are only an hour. By air is quick and easy but not the cheapest.
Stockholm to Helsinki by Ship
If you have some time to spare while traveling, there's a 16-hour ferry connection between Stockholm and Helsinki leaving in the afternoon and arriving the following morning. The Viking Line and the Tallink Silja Line ferries both cover Stockholm-Helsinki (and Helsinki-Stockholm), as does the once-a-week St. Peter Line. The ferries include onboard services such as bars, restaurants, different types of cabins and duty-free shopping. In addition to foot passengers, cars, motorbikes, and bicycles are allowed on the ferries.
The Viking Line offers cheaper cruise prices (from $61 one way) but uses older ships; Tallink Siljah Line cruises are more expensive (from $84 one way) but also offer more elegance. St. Peter Line is about $78 one way.
Booking a weeknight cruise from Stockholm to Helsinki is cheapest, and there's another discount if you buy a round-trip ticket.
This is a rather cheap way to get from Stockholm to Helsinki or back, albeit not very fast. (You could also take a ferry from Stockholm to Åbo, Finland, which takes 10.5 hours, and make your way south to Helsinki from there by bus or car.)
Stockholm to Helsinki by Train
There are no train connections between Stockholm and Helsinki. Take a look at the map of Sweden and imagine where the train would have to go...
Stockholm to Helsinki by Car
Much like the train method, there's no direct land connection between Stockholm and Helsinki. You'll have to take the 16-hour ferry if you want to take your car with you. Vehicle rates are reasonable, starting at around $125. Ferry destinations suitable for this option would be Helsinki City Center or Åbo, Finland.
Stockholm to Helsinki by Bus
Sorry, buses are not a viable option either. The only other option apart from flying is taking a ferry. If you're on a budget, try the cheap Viking Line and book a ticket as a foot passenger on a weekday.