The trough geomorphic feature layer represents the spatial extent of the troughs 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). The IHO (IHO, 2008) definition of a trough is ???a long depression of the sea floor characteristically flat bottomed and steep sided and normally shallower than a trench???. In this study we found that troughs are also commonly open at one end (i.e. not defined by closed bathymetric contours) and their broad, flat floors may exhibit a continuous gradient along a thalweg. Troughs may originate from glacial erosion processes or have formed through tectonic processes. In this study, glacial troughs incised into the shelf are a separate category; here we include all troughs not of a glacial origin, typically superimposed on the slope and/or abyssal base layers. Trenches that have been infilled with sediment may evolve into troughs, as appears to have occurred in troughs adjacent to North and South America, for example. Slumping on the sides of some troughs has formed a bridge across the trough, thereby dividing it into two separate sections (see ???bridges??? below). In this study all troughs were digitised by hand based on the interpretation of 100 m bathymetric contours.