There are regular and frequent ferry services from Stockholm, Sweden to Helsinki and Turku. Also some other cities along the coast can be reached from various cities in Sweden. These ferries take cars, too. Helsinki is served also by a ferry route from Travemunde, Germany. There's also frequent service from Tallinn, Estonia to Helsinki.
Many roads have breath-taking scenery.
Buses are a good alternative and they cover even the most remote parts of the country. There are express buses linking the major cities and local buses covering the rural areas. Finnair flies between major cities and most popular vacation sites in Lappland. When the sign is lit the taxi is vacant. All the taxies are connected to a phone call or reservation system.