A subsea assistance system for saturation divers, the system comprising: a UUV; items of ancillary electrical equipment that are connected or subsea-connectable to the UUV, those items comprising: at least one hand-portable subsea tablet arranged to display to a diver, subsea, an image corresponding to image data communicated to a display of the tablet from the UUV, wherein the tablet is diver-transportable away from the UUV to a subsea location remote from the UUV while remaining connected to the UUV by a display data link implemented by a first cable extendable from the UUV, which cable also conveys electrical power to the tablet; and at least one subsea camera arranged to capture image data, subsea, for communication to the UUV, wherein the camera is diver-transportable away from the UUV and from the tablet to a subsea location remote from the UUV while remaining connected to the UUV via a camera data link implemented by a second cable extendable from the UUV, which cable also conveys electrical power to the camera; and/or at least one subsea electrical tool that is connected or connectable to at least one wet-mateable electrical connector of the UUV via a third cable for conveying electrical power to the tool, wherein the tool is diver-transportable away from the UUV and from the tablet to a subsea location remote from the UUV while remaining connected to the UUV via the third cable; wherein the UUV comprises a communication device arranged to convey, via audio communication, instructions for using the camera and/or the tool from a diver holding the tablet to another diver holding the camera and/or the tool. a UUV; items of ancillary electrical equipment that are connected or subsea-connectable to the UUV, those items comprising: at least one hand-portable subsea tablet arranged to display to a diver, subsea, an image corresponding to image data communicated to a display of the tablet from the UUV, wherein the tablet is diver-transportable away from the UUV to a subsea location remote from the UUV while remaining connected to the UUV by a display data link implemented by a first cable extendable from the UUV, which cable also conveys electrical power to the tablet; and at least one subsea camera arranged to capture image data, subsea, for communication to the UUV, wherein the camera is diver-transportable away from the UUV and from the tablet to a subsea location remote from the UUV while remaining connected to the UUV via a camera data link implemented by a second cable extendable from the UUV, which cable also conveys electrical power to the camera; and/or at least one subsea electrical tool that is connected or connectable to at least one wet-mateable electrical connector of the UUV via a third cable for conveying electrical power to the tool, wherein the tool is diver-transportable away from the UUV and from the tablet to a subsea location remote from the UUV while remaining connected to the UUV via the third cable; at least one hand-portable subsea tablet arranged to display to a diver, subsea, an image corresponding to image data communicated to a display of the tablet from the UUV, wherein the tablet is diver-transportable away from the UUV to a subsea location remote from the UUV while remaining connected to the UUV by a display data link implemented by a first cable extendable from the UUV, which cable also conveys electrical power to the tablet; and at least one subsea camera arranged to capture image data, subsea, for communication to the UUV, wherein the camera is diver-transportable away from the UUV and from the tablet to a subsea location remote from the UUV while remaining connected to the UUV via a camera data link implemented by a second cable extendable from the UUV, which cable also conveys electrical power to the camera; and/or at least one subsea electrical tool that is connected or connectable to at least one wet-mateable electrical connector of the UUV via a third cable for conveying electrical power to the tool, wherein the tool is diver-transportable away from the UUV and from the tablet to a subsea location remote from the UUV while remaining connected to the UUV via the third cable; wherein the UUV comprises a communication device arranged to convey, via audio communication, instructions for using the camera and/or the tool from a diver holding the tablet to another diver holding the camera and/or the tool.