Getting there & away
Buses depart for Porvoo from the Helsinki bus station every 30 minutes or so (€8.70, one hour) and there are frequent buses to/from towns further east, including Kotka (€12.70) and Lappeenranta (€25.40).
The old diesel Porvoo Museum Train (752 3262; one way/return €12/20) runs between Helsinki and Porvoo on Saturdays in July and August. The train departs from Helsinki at 10.16am and from Porvoo at 4.30pm and takes 1½ hours; purchase tickets at the Helsinki or Porvoo train station or on board the train. In Porvoo, the train runs to a final stop near the main bridge, about 1km past the old train station. The trip can also be combined with a cruise on the MS JL Runeberg. It also does a trip from Porvoo to the village of Hinthaara between arrival from Helsinki and final departure.
The M/S JL Runeberg (524 3331; www.msjlruneberg.fi; adult one way/return €21/31, child €10/14), a former steamship, travels between Helsinki and Porvoo in summer and makes an excellent day trip. It leaves Helsinki daily (except Thursday) at 10am returning from Porvoo at 4pm, and arriving in Helsinki at 7.25pm. Since the trip takes four hours, you may want to return by bus or, on Saturdays in summer, on the vintage diesel train (adult/child combined ferry and train ticket €29/12).
An alternative is the modern, speedy M/S King, operated by Royal Line (09-612 2950; www.royalline.fi; one way/return €21/32). It travels from the Helsinki kauppatori at 10am daily bewteen late June and mid-August, returning from Porvoo at 3pm, taking three hours each way. It can be done as a day trip with an interesting archipelago cruise and two hours of sightseeing in Porvoo. The onboard lunch costs €12.