The Saronic (or Argosaronic) Gulf is set between Attica Prefecture and Peloponnese. Aegina, Angistri, Poros, Hydra, Spetses and Salamina (or Salamis) are the main islands of the Saronic Gulf, with Aegina, once a major rival to Athens, Salamina famous for its sea battles, Poros the island of Poseidon, Hydra and Spetses, which played an important role during the war of independence.
Today these islands make a good holiday resort, not far from Athens with Aegina to be in 1985 the most visited island in Greece. Cosmopolitan Hydra (no cars are allowed here) has a spectacular waterfront and attracts many artists. Spetses is a relaxed pine scented island and Poros is a busy (especially in weekends) pretty, fertile island, less than 400 meters away from Galatas town in Peloponnese. Agistri is a small island of pine woods and Salamina is just another suburb of Piraeus. Both Poros and Spetses can be reached by road and then cross from Galatas and Costa (in Peloponnese) respectively.
These islands are all within an hour or two from Athens by Flying Dolphin, which makes them not only convenient for day trips, but Aegina, Poros and Agistri can be used as a place to stay while commuting to Athens to see the sites. There are many ferries a day and Hydrofoils can run hourly or more.