A system allowing high-frequency sampling at several depths simultaneously have been developed. It could be used in a strong current area close to the coast with frequent 180° half-turn. It includes three main components: (i) a line able to sample at ten depths simultaneously, (ii) the Dynalest, a deep-towed depressor that maintains the line submerged at depth with a lift/drag ratio of 80, and (iii) an automatic high-frequency sampler with volume and flux control. The system was designed to collect samples for validation of 3D hydrodynamic models in the plume close to a seabed outfall with 4 m s−1 tidal currents (La Hague Cape). During sampling, the ship was operating normally at speeds of 0.5–5 m s−1 with frequent half-turns. Ten depth levels were sampled simultaneously every 30 s from 0 to 20 or 55 m depth. More than 13,000 samples were collected during a five days campaign. Vertical slices pictures of a dispersion plume where obtained each 5–10 min (100–200 measurements each one). The different parts of the system may be used separately or together. It can be adapted for varied conditions as greater depths, more vertical levels of simultaneous in-depth sampling or large volumes.