Wind farm cable length has a direct impact on the project cost, reliability, and electrical losses. The optimum cable layout results in a lower unit cost of generating electricity offshore. This paper explores three cabling structures: the string structure, ring structure, and multiloop structure on a three-dimensional seabed The newly proposed multiloop structure increases reliability and proves to be most economic when the failure rate and mean time to repair of cables are relatively high. Particle swarm optimization is used to find the optimal substation location that minimizes the overall cable distance.