01919nas a2200241   4500000000100000008004100001260001500042100001700057700001800074700001500092700001300107700002000120700001800140700002100158700002300179700002000202245007300222856004700295300001400342490000700356520130000363020001401663       2024                            d  c2024/08/011 aLewis Bailey1 aMichael Clare1 aJames Hunt1 aIan Kane1 aElda Miramontes1 aMarco Fonnesu1 aRicardo Argiolas1 aGiuseppe Malgesini1 aRegis Wallerand00aHighly variable deep-sea currents over tidal and seasonal timescales  uhttps://doi.org/10.1038/s41561-024-01494-2  a787-794, 0 v173 aDeep-sea transport of sediment and associated matter, such as organic carbon, nutrients and pollutants, is controlled by near-bed currents. On the continental slope, these currents include episodic down-slope gravity-driven turbidity currents and more sustained thermohaline-driven along-slope contour currents. Recent advancements in deep-sea monitoring have catalysed a step change in our understanding of turbidity currents and contour currents individually. However, these processes rarely operate in isolation and the near-bed current regime is still to be quantified in a mixed system. Such measurements are crucial for understanding deep-sea particulate transport, calibrating numerical models and reconstructing palaeoflow. Here we use 4 years of observations from 34 instrument moorings in a mixed system offshore of Mozambique to show that near-bed currents are highly dynamic. We observe spatial variability in velocity over tidal and seasonal timescales, including reversals in current direction, and a strong steering and funnelling influence by local seabed morphology. The observed near-bed currents are capable of mobilizing and distributing sediments across the seabed, therefore complicating deep-sea particulate transport and reconstruction of palaeoceanographic conditions.  a1752-0908