The creek is formed close to the village of Evigno (comune of Diano Arentino) from the union of several streams descending the south-eastern slopes of monte Torre (990 m).

[2] Going SSW, a direction the creek will keep till to its mouth, it reaches Diano San Pietro where it gets from the left rio Beste, its main tributary.

Not faraway from its mouth, which is located in comune of Diano Marina, the San Pietro is crossed by Genoa–Ventimiglia railway, Autostrada dei Fiori and State highway nr.1 (Via Aurelia).

San Pietro basin (18 km2) is totally included in the Province of Imperia.

[1] Media related to Torrente San Pietro at Wikimedia Commons