Demirköy is a small town in Turkish Thrace, backed by the wooded Strandzha mountains and close enough to the Black Sea wetlands at İğneada to make a varied day. The town itself is quiet, but the district has a strong identity: iron, forest, caves, and floodplain lakes.
The best local sight is the Demirköy Foundry, a ruined Ottoman industrial site where ore from the hills was worked for imperial projects. Farther into the forest, Dupnisa Cave is the showpiece natural attraction, with wet and dry chambers open to visitors in season.
Demirköy is not a polished resort, and that is part of the point. Use it as a base for the inland forest and the İğneada Floodplain Forests National Park, rather than expecting a busy town centre.