Abstract: A system (10) is provided for performing an operation on a subsea body (100), the system (10) comprises: a housing (20) configured to establish a sealed chamber around a section of the body (100); an environmental system configured to monitor and/or control an environment within the sealed chamber; and an operational tool (40) mounted to a positioning system (30) within the housing (20), wherein the operational tool (40) is configured to perform an additive manufacture operation on the body (100) within the sealed chamber. Also provided is a system (201) for performing an operation on an interior surface of a tubular body (200).