The fjords of Chilean Patagonia are areas of relatively rapid Holocene sediment delivery from glacial, glacifluvial and fluvial systems. These systems are fed by substantial ice- and snow-melt on the flanks of the Andean mountains. Many fjords are infilled by tens of metres of fine-grained, acoustically laminated sediment leading to a relatively flat and undifferentiated appearance of the fjord floor except where mass-wasting and turbidity-current processes are operating (e.g. DaSilva et al. 1997; Araya-Vergara 1999, 2008; Boyd et al. 2008; Dowdeswell & Vasquez 2013). In some areas, pockmarks have been observed on the floor of fjords, whose origin has been linked to the escape of fluids from the underlying sediments. During the analysis and interpretation of almost 27 000 km2 of multibeam-bathymetric imagery from the fjords of Chilian Patagonia between 47° 35′ S and 50° 17′ S (Fig. 1a), several relatively small areas of the fjord floor were identified as containing crater-like pockmarks (Dowdeswell & Vasquez …