A cooling apparatus comprising: a first outer portion comprising a fluid inlet, a first exterior cooling surface, and a first fluid-diverting structure in fluid communication with the fluid inlet, the first fluid-diverting structure comprising a flow diverter configured to facilitate heat transfer with the fluid; a second outer portion comprising a fluid outlet, a second exterior cooling surface, and a second fluid-diverting structure in fluid communication with the fluid outlet, the second fluid-diverting structure comprising a flow diverter configured to facilitate heat transfer with the fluid; an electrical substrate (75, 100, 135, 155) coupled to at least one of the first exterior cooling surface and the second exterior cooling surface; and an intermediate portion in a facing relationship with the first outer portion and the second outer portion, the intermediate portion defining an aperture for transferring a fluid between a first cavity and a second cavity, the first cavity defined between the first outer portion and the intermediate portion, the second cavity defined between the second outer portion and the intermediate portion; wherein the fluid is capable of being conveyed through the fluid inlet, the first fluid-diverting structure, the first cavity, the aperture, the second cavity, the second fluid-diverting structure, and the fluid outlet, to dissipate heat from the electrical substrate (75, 100, 135, 155), characterized in that the first fluid-diverting structure comprises a curved wall defining a first spiral fluid path configured to divert the fluid in a generally spiral pattern to the aperture, that the second fluid-diverting structure comprises a curved wall defining a second spiral fluid path configured to divert the fluid in a generally spiral pattern to the fluid outlet, and that the flow diverters (65, 127) of the first fluid-diverting structure and the second first fluid-diverting structure are protrusions provided within the first spiral path and the second spiral path and have a generally elliptical cross-section with the longer axis arranged in the flow direction of the respective path (60, 125). a first outer portion comprising a fluid inlet, a first exterior cooling surface, and a first fluid-diverting structure in fluid communication with the fluid inlet, the first fluid-diverting structure comprising a flow diverter configured to facilitate heat transfer with the fluid; a second outer portion comprising a fluid outlet, a second exterior cooling surface, and a second fluid-diverting structure in fluid communication with the fluid outlet, the second fluid-diverting structure comprising a flow diverter configured to facilitate heat transfer with the fluid; an electrical substrate (75, 100, 135, 155) coupled to at least one of the first exterior cooling surface and the second exterior cooling surface; and an intermediate portion in a facing relationship with the first outer portion and the second outer portion, the intermediate portion defining an aperture for transferring a fluid between a first cavity and a second cavity, the first cavity defined between the first outer portion and the intermediate portion, the second cavity defined between the second outer portion and the intermediate portion; wherein the fluid is capable of being conveyed through the fluid inlet, the first fluid-diverting structure, the first cavity, the aperture, the second cavity, the second fluid-diverting structure, and the fluid outlet, to dissipate heat from the electrical substrate (75, 100, 135, 155), characterized in that the first fluid-diverting structure comprises a curved wall defining a first spiral fluid path configured to divert the fluid in a generally spiral pattern to the aperture, that the second fluid-diverting structure comprises a curved wall defining a second spiral fluid path configured to divert the fluid in a generally spiral pattern to the fluid outlet, and that the flow diverters (65, 127) of the first fluid-diverting structure and the second first fluid-diverting structure are protrusions provided within the first spiral path and the second spiral path and have a generally elliptical cross-section with the longer axis arranged in the flow direction of the respective path (60, 125).