Fig. 3

Ag. Kiriaki (A): a) water column depiction above the illustrated area, coordinates: 36°38.824’ N, 24°29.4516’ E, b) ROV photo above the seafloor at the area of Ag. Kiriaki with patches of bacterial mats on the sediments, c) AUV bathymetric map illustrating the morphology of the depressions formed due to hydrothermal activity. Paleochori-Thiorychia (B): d) water column depiction above the “Celestial Chimney”, coordinates: 36°42.0233’ N, 24°35.6548’ E, e) ROV photo of the “Celestial Chimney” partly covered with white bacterial mat (GeoB255-20), f) AUV bathymetry combined with multibeam data to illustrate the morphology of the seafloor east of Paleochori-Thiorychia. Vani (C): g) water column depiction above the illustrated active area of Vani, h) ROV photo above a highly active area with boulders covered partly with bacterial mat and yellow sulfur precipitated (GeoB255-36), coordinates: 36°46.6873’ N, 24°20.9174’ E, i) AUV bathymetric map illustrating the morphology of the vent field within the Vani graben.