Right opposite the beach of Kefalos, on the southern side of Kos island is the tiny Kastri islet. It is totally rocky and barren with little vegetation. Some remains of an old castle lie on top of this rocky islet that used to guard the bay from enemies and pirates. On the other side, there is a small chapel in blue and white colors dedicated to Saint Nicolas, the saint protector of sailormen. Kastri islet can be reached by boat or swimming from Kefalos beach.