A fire resistant and water resistant enclosure for an operable computer digital data storage device is provided. The enclosure has walls made of gypsum or concrete and, in one embodiment, has two small ventilation openings which remain open during normal operation of the digital data storage device and during the presence of fire. This embodiment has no moving parts. In the presence of fire, air and superheated steam from inside the enclosure expand and flow outwardly through the ventilation passageways. As those gases flow outwardly, they simultaneously block or prevent the transfer of heat from the exterior fire inwardly through those passageways. A water resistant pouch or coating surrounding the storage device prevents damage from flood, water, steam generated by the insulation or smoke from passing through said passageways and damaging the storage device. Another embodiment is provided utilizing one or more movable hatches which, in the presence of fire, cannot completely close, allowing superheated steam to escape from the enclosure yet during normal operation allow for better ventilation and cooling. A method is also provided for protecting the data storage device wherein the walls of the enclosure are supersaturated with water. The walls are coated with a vapor barrier such as plastic skin, plastic container or wax to prevent evaporation of water. In the presence of fire, the vapor barrier melts and the excess water stored in the walls absorbs latent heat of vaporization and extends the amount of time over which the enclosure is able to protect the storage device from damage.