On the norteastern part of the island, after you leave Therma and the campings behind, you'll find a beach which is called after Fonias, the most famous river of Samothrace. It's a lonely beach, with gray gravel and blue waters. On one side, near the mouth of the river there's the Fonias Tower, which was built by Gateluzzi during its works of fortifying the island.
The Fonias Tower before the flood of 2017
Sunset on Fonias Beach