The NW submarine portion of Stromboli volcano has been investigated by deep-towed sidescan sonar, bathymetric surveys, video camera runs and dredging during two research cruises in 2002 and 2004. The surveys resulted in the identification of an extensive pillow lava field (106-107m3) at about 2300 m of water depth and 9 km from the shoreline of Stromboli Island. The pillow lavas have a unique composition that does not match any known subaerial product, although a limited affinity exists with those erupted during the Neostromboli eruptive cycle of the island (13–6 ka). This is the first finding of a submarine eruption on the northern side of Stromboli and improves the knowledge of its flank activity and volcanic hazards. This eruption is interpreted as marking the onset of a new volcanic cycle from the edifice periphery fed by a new, distinct magma mixed with traces of the previous magma that survived the emptying of the Neostromboli magma chamber.