Agistri is a tiny and beautiful island and municipality in the Saronic Gulf, Greece. It's one of very few permanently inhabited greek islands, when during the season you can legaly (maybe not 100% legally, but police will not bother you) camp for free. Although the first what you will see after getting off the ferry is sign saying: "Camping is strictly forbidden". There are three settlements on island.
You can get to Agistri only in two ways - either you take a ferry or hitchhike the boat. Ferry departs from Pireus and a single ticket (one way) costs 10,9 euro. Hitchhiking the boat is rather hard. You can ask sailors in athenian's harbors. There are four types of transport on the island. There are buses going through island and villages every hour or so, there are taxis and you can rent some vehicle. But why to do it since hitchhiking works perfectly (there is no heavy traffic)?
On the island there are two places where you can camp for free. First one is in town Skala. When you leave the ferry just turn left and go straight on for about 10 minutes until as you reach the campsite. Place is very close to the civilization, so everything is at the fingertips. The second one is in Dragonera - three kilometers away from Skala. There is nothing there except a nice beach and a little canteen, where you can buy coffee, water or small meal. If you have any doubts you can ask locals or waiters for directions. In both places you can put your tent up and stay as long as you wish. The hotel's prices on the island start from 25 euro/room.
Because of relatively large (not as large as in Famous islands like Crete, Mykonos, Zakyntos etc.) amount of tourists, table diving is easy during the season. You can also ask in bakery for yesterday’s bread.
In many restaurants there is wi-fi.
Since there are plenty of tourists, you can easily try.