The central peninsula is small enough to walk almost everywhere — most sights are within a 25-minute stroll of Senate Square. For longer hops, the integrated HSL network covers trams, the metro, buses, the local trains, and the Suomenlinna ferry on a single ticket.
A single ticket (€3.10) is valid for 80 minutes; a 24-hour card (€9) pays for itself with three rides. Buy from the HSL app, ticket machines at any stop, or in person from the booth at Central Station. The metro is a single line that crosses the bay to Espoo in the west; the tram network is the more useful tool for the central peninsula and the inner suburbs. Bicycle hire (Helsinki City Bikes) operates from April to October with stations at every metro stop.