The locals call this area Gaidouronisia (donkey islands) and it’s a gathering of small islands just under 2 miles off the coast of Ouranoupolis and Ammouliani.
You may go there by renting a boat from Ouranoupoli. (no license needed).
Another way of reaching the Drenia islands is by the kaiki boats which leave from the main harbour of Ammouliani starting at 12:00 pm and go back at 18:00 pm, daily.
There is a lovely tavern and a small beach bar awaiting you!