The trench geomorphic feature layer represents the spatial extent of the trenches of the worlds oceans based on interpretation of the SRTM30 plus v7 global bathymetry model. The layer is one of the 25 layers that make up the global seafloor geomorphic features map (Harris et.al. 2014). Trenches are ???a long narrow, characteristically very deep and asymmetrical depression of the sea floor, with relatively steep sides??? (IHO, 2008). Trenches are generally distinguished from troughs by their ???V??? shape in cross section (in contrast with flat-bottomed troughs). In this study trenches were mapped by selecting closed bathymetric contours that defined basins contained within the trench feature, and then joining the basin segments together by hand digitizing along more elevated sections. In this way, bridge features were also identified (as coinciding with infilled sections of trenches; see section on ???bridges???).