Boat and Ferry
Spetses is so close to the Peloponnese mainland that you can drive there from Athens, park, and cross the channel in any of a number of caïques (price negotiable) at the ports, but to get to any of the other Saronic Gulf islands, you must take to the sea in a ferry. You can get a weekly boat schedule from the Greek National Tourism Organization (www.visitgreece.gr). You can get detailed info about ferry schedules at www.ferries.gr, ferriesingreece.com, or the handy app www.nisea.co, and you can also reserve through a travel agent. Large ferries are the leisurely and least expensive way to travel; however, most people prefer the speedier passenger-only "flying dolphins" (and be aware that there's also a ferry company called "Aegean Flying Dolphins") and hydrofoils.
Hellenic Seaways, ANES Ferries, and Nova Ferries will carry you and your car from the main port in Piraeus (Gate E8), about a thousand feet from the metro, to Aegina (1 hour). There are approximately a half dozen daily departures, and boat fares begin at about €8 per person for Aegina, from €20 for cars (there are no slow ferries to Hydra or Spetses). Speedier Hellenic Seaways and Aegean Flying Dolphins ferries and hydrofoils also depart from Piraeus (Gate E8 or E9). These faster ferries can get you to Aegina in 40 minutes (€13), to Hydra in 90 minutes (€28), and to Spetses in just under two hours (€38.50). There are about a half dozen departures daily to each island, but make reservations ahead of time—boats fill quickly.
What about boats and ferries between the various Saronic Gulf islands? Hellenic Seaways fast-ferry routes connect Piraeus to Hydra and Spetses year-round. There are about five daily round-trips from October to April, more the rest of the year. In summer, Saronic Ferries offers daily service that connects Aegina with the tiny islands of Angistri, Poros, and Methana. But plan your Argo-Saronic island-hopping carefully in the off-season. During that time, boats between the islands are much less frequent, and you may have to combine several ferries to reach your destination, some fast and some slow. And connecting service is not available every day; on some days (and in some seasons), you will have to backtrack to the main port at Piraeus to catch another boat. For information regarding specific ferry companies, see Boat and Ferry in Travel Smart.