As part of the the CHIMNEY project (NERC grant NE/N016130/1), multibeam bathymetry data were collected during RRS James Cook cruise JC152 to a subsea chimney structure in the northern North Sea around Scanner Pockmark in August-September 2017. Multibeam data were acquired using a Kongsberg EM-710 multibeam echosounder and processed by the JC152 Science Party. In conjunction with seismic profile data acquired on the same cruise, these data will help scientists understand the surface and internal structure and origin of the chimney structure. This will facilitate estimation of the permeability of the chimney and its surroundings, and enable leakage pathways to be determined. The potential for past oil and gas reservoirs and saline aquifers to be used as Carbon Capture and Storage (CCS) reservoirs of atmospheric CO2 can subsequently be explored. The safety of storing CO2 in such reservoirs is dependent on fully exploring the risks of any leakage via such chimney structures, which the CHIMNEY project will investigate. CHIMNEY is funded by the Natural Environment Research Council (NERC), and involves scientists from the National Oceanography Centre, Southampton and the University of Edinburgh. Investigators will work closely with project partners GEOMAR, Lawrence Berkley National Laboratory, CGG and Applied Acoustics. The project is complementary to the EU-funded Horizon 2020 project: Strategies for Environmental Monitoring of Marine Carbon Capture and Storage (STEMM-CCS).