From 9 to 15 December 2020, documentation activities of the archaeological evidence took place on the island of S. Nicola. These investigations are part of a new study project that intends to investigate the ancient population of the Tremiti islands through the most up-to-date techniques and methodologies of archaeological research. The island of S. Nicola is characterized by the presence of a natural depression in the rock (the so-called Tagliata) which divides it into two areas: to the south-west is the locality of S. Nicola di Tremiti (which includes the pier and, in an elevated position, the structures of the castle and the former monastery); while to the north-east there is a rather large terrace (1 km long and 22 hectares wide), with meadows, uncultivated land and natural pasture areas. This sector of the island now appears almost uninhabited and is characterized by a settlement with scattered houses (some in disuse). During this first topographical survey, the archaeological evidence of this sector of the island was documented: a watchtower; the so-called cistern of the Benedictines; a “Hellenistic” necropolis with Diomedes’ tomb; a vast multi-layered architectural complex in which the remains of a cryptoporticus can be recognized. This structure is located at the point of the island that offers maximum visibility of the surrounding area (73 m a.s.l.), halfway between the Tagliata and the north-eastern limit of the plateau. The cryptoporticus has a system consisting of three arms arranged in a U shape that occupy an area of ​​approximately 275 m2 (approximately 25 × 11 m).