Following successful deployment and testing in December 2020, the Helgoland Underwater Observatory (HUWO) equipped with a CPICS plankton and particle imager as well as CTD, oxygen sensor and ADCP, is now fully operational. This structure is one key element of the JERICO-RI North Sea Pilot Supersite (PSS) and is maintained jointly by Hereon (formerly HZG, K.O. Möller) and AWI (P. Fischer). The HUWO’s main element is a lander structure, which can be programmed to move vertically through the water column with remotely controlled winches, utilising the buoyancy of floats attached to its outer edges for the upward movement and straps connected to the winch and anchored to a base on the seafloor to move down.…