GSR successfully performed its fourth multidisciplinary offshore campaign in the Clarion-Clipperton Fracture Zone from 03/02/2018 to 27/03/2018. Although the fourth campaign for GSR, this expedition was the first in the claim area of the Cook Islands Investment Corporation (CIIC). In 2016, the CIIC (with GSR as technical partner) signed a contract with the ISA for the exploration of polymetallic nodules. The main purpose of the campaign was to survey more than half of the license area (41,000 km²) by using a hull-mounted multibeam echosounder for bathymetry and define potential resource fields of polymetallic nodules. The backscatter intensity of the multibeam data, indicator for seabed types, was validated using box-core samples and deep-towed imagery survey safely operated from the research vessel, at an average water depth of 4500m. GSR was also able to recover its environmental short moorings, launched during the preceding mission, and download 8-months record of deep-sea currents. Moorings were re-deployed shortly after recovery and will continue to record deep-sea currents until the next expedition in 2019. This expedition marks an important milestone in the partnership with the CIIC.