Submarine power cables (SPCs) are subjected to complex mechanical loadings during service, including tension, bending, torsion, and their combinations. However, systematic studies on the behavior of SPCs – particularly multi-core configurations – under such combined environmental loadings remain limited. This lack of comprehensive analysis hampers a full understanding of their mechanical responses and consequently restricts the design and development of these critical structures. Building upon our previously validated Representative Unit Cell (RUC) model for local mechanical analysis under pure tension and pure bending, this paper extends the investigation to a three-core SPC under a range of combined load cases. In addition, full-scale models are developed to study the torsional response in greater detail. The findings of this study provide valuable guidance for cable engineers, offering new insights into the internal interactions within SPCs and supporting more robust cable design.