Cooling apparatus and method are provided for immersion-cooling of an electronic subsystem of an electronics rack. The cooling apparatus includes a housing at least partially surrounding and forming a sealed compartment about the electronic subsystem and a dielectric fluid disposed within the sealed compartment so that the electronic subsystem is immersed within the dielectric fluid. A liquid-cooled vapor condenser is provided which includes a plurality of thermally conductive condenser fins extending within the sealed compartment. The condenser fins facilitate cooling and condensing of dielectric fluid vapor generated within the sealed compartment. Within the sealed compartment, multiple thermally conductive condenser fins are interleaved with multiple electronic components immersed within the dielectric fluid to facilitate localized cooling and condensing of dielectric fluid vapor between the multiple electronic components.