Tethers provide services similar to those of the Main Lift Cable, however in this case between the vehicle and either the TMS or the surface directly. Electrical & optical signal, electrical power and mechanical strength can again be custom designed into a suitable cable package by Cortland Fibron.

ROV tethers can significantly affect vehicle performance, so are invariably required to be highly flexible and robust. Small diameter is crucial, and neutral to positive buoyancy is frequently an indispensable requirement.