An evaporative cooling device (40) is disclosed for cooling water or other liquids comprising a vessel (50) adapted to receive water or another liquid, said vessel comprising a vessel wall (53, 54, 55), an outer layer (90) of absorbent material and a wick (85) extending through said vessel wall, such that said wick is positioned to contact said water or other liquid within the vessel and is adapted to transport a portion of said water or other liquid through the wall by capillary action to said absorbent material, said wick being substantially impermeable to gas or vapour, so that the cooling device (40) can be connected in-line in an hydration system of the kind comprising a reservoir (12) and a drinking tube (32). Water or other liquid transported from within the vessel to the outer layer by said wick is absorbed by the absorbent material, from which it evaporates, the latent heat required for such evaporation being removed from the water or other liquid disposed within the vessel as sensible heat through the vessel wall, thereby cooling such water or other liquid. In some embodiments, the cooling device (40) may be fan-assisted. Also disclosed is a cooling garment comprising a garment portion that is adapted to be worn by a user and an evaporative cooling device (40) for cooling water or other liquids that are circulated through integrant channels or tubes provided in the garment.