Abstract: The vent structure comprises a durable material wherein a tortious pathway is provided for gas to flow into and out of a storage tank. The tortious pathway is defined by a plurality of baffles that depend or extend from the inner surface of the vent structure. Further protection of the storage tank contents is provided by employing mesh screen covers over the openings to the vent structure and to the storage tank. Unauthorized disassembly of the vent structure is assisted by using support columns that extend from the cover to the bottom of the vent structure. A terminal portion of each support column may be adapted to pass through a portion of the vent structure and receive a lock. Thereby, an intruder resistant vent structure deters unauthorized access to a storage tank which is particularly useful for protecting a water storage tank.