Castro Marina is an adorable seaside town in southern Puglia. At the beginning of the tourist season, it's very tranquil. While it isn't very big, there are two areas you can explore:
1. The historic center with the Byzantine church (Church of Saint Mary of the Annunciation), castle, and viewpoints overlooking the sea.
The marina area with the two little ports, where you'll also see a concrete area where the locals go into the water.
From this town, you can also take boat tours to see the coast and sea caves of this area in Salento.