The aim of this paper is to present a methodology for selecting proper voltage level and power cables as a part of the AC distribution system design for subsea vehicles, such as Remotely Operated Vehicles, seafloor trenchers and subsea mining machines. The design methodology encompasses a wide range of cable lengths and load power demands (up to 7 MW). Furthermore, both electrical and mechanical considerations have been taken into account in order to provide an optimum design for the power cable. The final decision is made considering the main parameters including voltage drop, power loss, reactive power exchanged in the cable, conductor cost, and top and bottom tension forces acting on the cable.