This article originally appeared in the August/September 2023 issue of Dream of Italy. For an unexpected adventure in Puglia, an area loved by sun-worshiping beachgoers, look deeper. About 200 feet deeper, to be exact. Half an hour’s drive from the azure waters of Polignano a Mare, the Grotte di Castellana look more like another planet than Puglia. The 100-million-year-old karst cave system…