By Plane -- From Athens, there are usually two flights daily on Olympic Air; fares in high season can vary from 60€ to 110€. The Argostoli office is at 1 Rokkou Vergoti, the street between the harbor and the square of the Archaeological Museum (tel. 26710/28-808). Kefalonia Airport is 8km (5 miles) outside Argostoli. As there is no public bus, everyone goes to Argostoli by taxi, which costs about 15€.
By Boat -- As with most Greek islands, it's easier to get to Kefalonia in summer than in the off-season, when weather and reduced tourism eliminate the smaller boats. Ferries to Kefalonia are operated by at least four lines: Strintzis, Agoudimos, Endeavour, and Ionian; check out their schedules at www.gtp.gr or www.ferries.gr. If you don't make arrangements with a travel agent, you can buy tickets dockside. Throughout the year, a car-passenger ferry leaves daily from Patras to Sami (about 2 1/2 hr.). There is also at least one car-passenger ferry daily (1 1/2 hr.) from Killini (on the northwest tip of the Peloponnese) to one of several ports of Kefalonia -- Argostoli, Sami Lixouri, or Poros. To give some idea of the cost, a round-trip Patras-Kefallonia-Patras trip for a couple with their own cabin would be about 150€.
Beyond these more or less dependable services, during the months of July and August, there are alternatives -- ships to and from Corfu, Ithaka, Levkas, Brindisi (Italy), or other ports -- but they do not necessarily keep the same schedules every year.
The Argostoli Tourism Office, in Argostoli, is at the Port Authority Building, on Ioannis Metaxa, along the harbor (tel. 26710/22-248). It's open in high season daily from 7:30am to 2:30pm and 5 to 10pm; in low season, hours are reduced to Monday through Friday from 8am to 3pm.