Methods and apparatus for cleaning geophysical equipment, using a streamer cleaning unit (SCU) and a remotely operated vehicle (ROV), whilst being towed

Methods and apparatus relating to the cleaning of geophysical equipment (eg. a streamer) whilst the equipment is submerged and being towed by a vessel, 105. In one embodiment, a remotely operated vehicle, 200, (ROV) is used to facilitate cleaning the equipment. The ROV may load a streamer cleaning unit, 205, on to a streamer, 104, which facilitates cleaning by propelling itself along the streamer. In a second embodiment an interface unit is configured to receive commands from a remote location and a cleaning unit is configured to respond to the received commands. The ROV, 200, may be configured to attach and remove a self propelled cleaning unit, 205, to the streamer, 104, or to remain attached and propel the cleaning unit itself. In a third embodiment the ROV may attach the cleaning unit to the streamer, detaching the unit and then subsequently reattaching it to another streamer.