Petra lies about an hour northeast of Skala Eressos - in the same direction as Mithymna - and its beach is one of the most popular on the island. It has the vibe of a resort with sunbeds, changing stations, public bathrooms, and umbrellas, but can get a little crowded in the high summer season. A row of high-quality restaurants and shops are steps away, and the whole town of Petra is worth exploring.