Capo Mannu / Is Arenas
In the Quaternary it was an ancient island which, following the deposition of imposing masses of sediment, connected to the mainland through large strings of sand; these processes have established an advancement of the coast which, joining the coast to the promontory of Capo Mannu, has enclosed the stretches of Sa sandy water are called tomboli, in the case of Capo Mannu it is a double tombolo.
The promontory is of considerable importance due to the presence of a complex of layered fossil dunes about 60 meters which, by thickness, is the only one in Italy; these dunes originated following the deposition of imposing quantities of sand due to the spread of very strong winds in a not entirely precise period (end of the Pliocene or beginning of the Quaternary). The Cape, formerly inhabited, preserves many testimonies of human settlements such as the hypogeic necropolis of Putzu Idu, which was of great importance as a place of passage and stop for merchant traffic since the 4th century. B.C.
During the Roman period, the Sa Salina Manna and Sa’e Proccus lagoons were used for the collection of salt which was embarked in the port center of Koracodes Portus, a location presumably located near the tonnara.
The vegetation consists of species with a prostrate and creeping appearance, natural adaptation against the action of the wind, salt and sand. It is a rich and precious vegetation: recent studies have surveyed more than 400 plant species, many of which are endemic or exclusive to the area. Between the maquis, essentially made up of Phoenician juniper, it is possible to see the small violet of the Sinis (Viola Arborescens) which bloomed between April and May, and the Poligala Sinisica, two rare endemisms of the Sinis. Further inside the bush is enriched with colors and shapes due to the presence of rosemary, mastic, heather, and broom. Still among the endemic species is the yellow Helianthemum caput-felis, a cistacea that has chosen the Capo Mannu peninsula as its only development site.
One of the largest beaches in Sardinia, exposed to the predominant mistral wind, represents the largest dune complex in Europe, within which, precisely to stop the advancement of the sands due to strong winds, has been planted, with a large reforestation project, a large pine forest. The beach is characterized by its yellowish color, by the presence of numerous shells of various bivalves and the marine balls generated by the action of the waves on the seagrass plants detached from the seabed. Interesting the recent discovery, in the southwest side of the beach of the remains of a Roman well and walls that would represent the remains of an ancient port.