A heat dissipating device includes a sealed container having hollow floors and floor-spacing assemblies. Each floor-spacing assembly includes hollow spacing walls. Each hollow spacing wall extends from a respective hollow floor and is spaced apart from an adjacent one of the hollow spacing walls of an adjacent one of the floor-spacing assemblies by an air gap. Each two adjacent ones of the hollow floors are interconnected through the hollow spacing walls disposed therebetween. The sealed container defines a liquid reservoir, a condensate reservoir, and a plurality of fluid passages extending through the hollow spacing walls and the hollow floors that are disposed between the liquid reservoir and the condensate reservoir.