There is a growing interest in the application of submerged rubble mound breakwaters as coastal defence structures. As their defensive ability highly depends on the amount of wave energy remaining at their lee side, the accurate prediction of the energy in the lee of such structures is of utmost importance. Past experiments have shown that the behaviour of rough permeable rubble mound structures under oblique wave attack was found to be significantly different from that of smooth impermeable low crested structures. This behavioural difference has led to the research objective of this present study which is to investigate oblique wave transmission by rough impermeable rubble mound submerged breakwaters using 3D physical model tests. This study intentionally uncouples two parameters, being the permeability of the core and the roughness of the breakwater. Analysing the data of this study shows that the permeability of the core has no visible influence on the structure's behaviour with respect to the influence of oblique wave attack. The fully permeable rough rubble mound breakwater behaves analogous to the fully impermeable rough rubble mound breakwater