Geo Oceans and Vertech used Mini-ROV systems, specialised actuator systems, and ACFM equipment to measure and map crack indications in water ballast tanks for Australia’s largest oil and gas operator. Prior to mobilisation a desktop 3D modelling exercise was performed to confirm ROV and tooling access to all anomalies, and to facilitate tooling design modifications. Five ballast tanks were surveyed, with the ROVs operated from a workshop module on the FPSO up to 150 m away from the tank entry.