Meiofauna samples were collected during SO261 in 2018 using a multi-corer at six hadal sites along Atacama Trench axis, two abyssal sites on each side of the trench and on the bathyal site on the Chilean slope. Sediment cores were sliced at a depth resolution of 1 cm down to 5 cm depth and the layers were fixed in 4% buffered formalin. Sediment samples were sieved and rinsed on a 20 µm mesh size for meiofauna analyses. Organisms were counted using a stereomicroscope and measured using a light microscope.