This system is designed to be accommodated on AWI’s in house developed underwater-winches (Lochthofen et al. 2021), which are designed to be deployed on moorings for year-round operation. It is consisting of a camera housing incorporating an industrial camera with 4Mpixel and a computing unit as well as a light source housing to obtain shadow images of particles with a resolution of 5,5µm and a volume of 50mL per image. In operation the system acts as slave of the winch. During a profile the (usually from 150 m to 10m below sea level) the winch triggers the camera image acquisition followed by online image processing and sending the data back to the winch system to be available in case of loss of the profiling unit of the winch system, where the camera is mounted on. Furthermore, all data is collected in the camera for postprocessing after retrieval.