Saronic Gulf, Greek Islands
Saronic islands are all within an hour or two from Athens by Flying Dolphin, which makes them not only convenient for day trips, but Hydra,Spetses,Aegina, Poros and Angistri can be used as a place to stay while commuting to Athens to see the sites.
There are many ferries/boats ,mini taxi cruise, a day and Hydrofoils can run hourly or more.
Aegina island
was a city state in it's own right in ancient times, and at times a visible thorn in the side of classical Athens. Aegina is a vert nice day trip from Athens. Take the ferry rather then the hydrofoil so that you can relax and enjoy the scenery of the short trip...
Angistri,
is a small island near Aegina with beautiful sandy beaches and a devoted following. Angistri is famous for being one of the first places in Greece to experiment with naturalism, (or in plain English it was one of the first islands to
have a nudist beach)...
Hydra,
Former home of Leonard Cohen and jet setter haven. No beaches but who cares? Magnificent village and swimming off the rocks is good enough for recovering from the previous nights festivities. Restaurants and cafes on waterfront are for people-watching 
Spetses,
Nice beaches. Pine trees. Water-taxis and Nightlife in the old harbor plus one of the oldest wooden boat building yards in Greece. Spetses is most famous for being the setting for the John Fowles book The Magus which is suggested reading for your visit here.You can travel all around the island by bicycle or water taxi and there are excursion boats and buses to the various beaches...
Poros
Imagine an island so close to Athens that you can wake up in the morning and in a little more than an hour, be walking around the acropolis, shopping in the flea-market or wandering around the Plaka looking for gifts or a nice place for lunch. Imagine an island that is a three minute boat ride to the Peleponisos and places like

Salamis island
According to myths and legends Salamis is named after the Nymph Salamina the daughter of the Corinthian river Asopou and Koulouri from the ancient cape (Kolouris Akra) where the ancient city was built in 4thcentury.  According to myth , Poseidon fell in love with Salamina and she gave birth to Cychreus the first king of Salamis who was half man half fish.The next king of Salamis was Telamon who married the daughter of Cychreus, Glauce. After her death he married Erivia or Periboea and the legendary AIAS (AJAX) was born, who was the leader of the Salaminian and Megarian army at the Trojan war. Ajax (Aias) had a half-brother from Hesione whose name was Teucros, they both took part in the great Trojan war having 18 ships under their command. After the Trojan war and the suicide of Ajax (Aias), Teucros along with the son of Ajax (Aias), Eurysaces, returned to Salamis and faced the anger of Telamon, because Teucros did not revenge the death of his brother, Ajax (Aias). Teucros abandoned the island and went to Cyprus were he established a new city, naming it after his birth place, Salamis. Salamis Island was inhabited from the Neolithic centuries, as the archeological findings reveal on the southern part of the coast of the island. Because of it’s geographical location it was the reason of many disputes from the larger cities that wanted to control the island. The greatest event of Salamis history is the great battle of Salamis, which changed the course of history at that time, where the Greeks defeated the Persians and ended the quest of the Asian barbarians to conquer Greece and Europe.
On Salamis island at the time of the great battle of Salamis the three greatest play writers of all centuries met. Aeschylos, who took part in the Great Battle of Salamis and afterwards wrote it’s history, Sofoclis, a teenager at the time, took part in the victory celebrations and last but not least comes the most tragic of the three Euripides, Who was born on Salamis on the day of the Great Historic Event. read more about Salamis island http://www.salamina.gr/english/history.htm