A water block for cooling a heat-generating component has a body defining an internal fluid conduit for circulating fluid within the water block. The body defines a fluid inlet and a fluid outlet for feeding fluid into and discharging fluid from the internal fluid conduit respectively. The body includes: an external thermal transfer surface configured to be in contact with the heat-generating component; an opposite external surface on an opposite side of the body from the external thermal transfer surface; and at least one hollow fin extending from the opposite external surface, the at least one hollow fin defining at least one external fin passage, each of the at least one hollow fin defining an internal fin recess that forms part of the internal fluid conduit of the water block.