This geophysical survey has been carried out by, British Geological Survey (BGS), the survey took place in July 1991 in the North Sea on board the RRS Challenger. The purpose was to collect data to investigate gas-leakage phenomena from pockmarks in the North Sea. Sea floor data were collected using Sidescan Sonar. Sub-bottom profiling data were collected using Deep Tow Boomer. These data were recorded digitally and are archived by BGS. Cruise report available at https://www.bodc.ac.uk/resources/inventories/cruise_inventory/reports/ch82_91.pdf.