Most of the monasteries of Skiathos date back to the time of Turkish occupation. They helped the islanders both materially and morally. Among the monasteries of Skiathos, some have been completely destroyed, some are in ruins (the monastery of St. John of Parthenis, the monastery of Our Lady of Kechria and the monastery of St. Charalambos). Two monasteries have been preserved in good condition and are worth a visit.

The monastery of the Annunciation (Evangelistria). This is the most appealing of the island's monasteries. It is in a delightful setting, poised above a gorge, 450 meters above sea level, built on a beautiful site but invisible from almost all directions. The monastery is an hour's walk from town or you can get there by rented moped, car or mule. It is open daily 8am-noon, 4-8pm. To reach it, walk 500m out of the centre of town on the road towards the airport until, at the point where the asphalt veers to the right, you take a prominently signposted tarmac track that veers left. Be careful to stick to the tarmac and not to wander off onto the dirt road.

When the monastery was completed in 1806, it was called the "new monastery" in order to distinguish it from the other monasteries of the island which were older. It was generous in offering its services and often helped the inhabitants of Kastro and supported the needy. The monastery, like many in Greece, was a refuge for freedom fighters during the War of Independence, and the islanders claim the first Greek flag was raised here in 1807.

The monastery of Panaghia (Holy Virgin) Kounistra. This is where the holy icon of Panaghia Kounistra was found, and where it was also initially kept. The Panaghia Kounistra is the patron of Skiathos.  To reach the monastery, turn right off the road that runs from Troulos to Asselinos. It is a very pretty spot, has a grape arbor and a taverna within its walls. The founding of the monastery is related to the finding of the icon, around the end of the 17th century. The church of Panaghia Kounistra is a single-naved basilica with dome. The interior is painted. The gilt wooden iconostas is beautifully carved and decorated with vine-leaves and grapes. At the entrance to the monastery there is a painting of the Annunciation of the Virgin and in the wall on the left is a marble sundial.