(a) Morphological and structural arrangement of the continental shelf and Gulf of Naples15,23,24,48. Dots are the main submarine eruptive centers; the red lines represent the main faults. (b) Bathymetry of the Gulf of Naples with the detected fluid vents (dots) and the trace of the seismic lines (black lines). Yellow lines are the traces of the seismic lines L1 and L2 reported in Fig. 6. The boundary of the Banco della Montagna (BdM) dome-like structure is marked by a bleu dashed line in (a,b). Yellow squares mark the location of the acoustic water column profile, CTD-EMBlank, CTD-EM50 and ROV frame reported in Fig. 5. Yellow circles mark the location of the sampled gas discharges, whose composition is reported in Table S1. Figure generated with Surfer® 13 by Golden Software (http://www.goldensoftware.com/products/surfer).