A nacelle for a turbofan engine having an engine centerline, the nacelle comprising: a forward assembly that defines a bypass duct extending circumferentially at least partially around the engine centerline, the bypass duct being configured to transport bypass airflow of the engine, the forward assembly having an aft edge that extends circumferentially at least partially around the bypass duct; a variable area fan nozzle (VAFN) disposed behind the forward assembly and movable relative to the forward assembly between a stowed position and a deployed position, an upstream bypass flow exit for the bypass duct being defined between the forward assembly and the VAFN when the VAFN is in the deployed position, an outer surface of the VAFN providing an aerodynamic boundary for bypass airflow exited through the bypass flow exit; and a seal attached to the forward assembly, the seal including an inner wall and a plurality of webs attached to the inner wall and extending transversely there-from, each of the webs extending circumferentially at least partially around the bypass duct, the inner wall defining an exposed inner surface that extends circumferentially at least partially around the bypass duct, the inner surface providing a substantially smooth aerodynamic boundary for bypass airflow exited through the bypass flow exit when the VAFN is in the deployed position, at least a portion of the inner surface interfacing with the VAFN outer surface when the VAFN is in the stowed position so as to seal the bypass flow exit, each of the webs having a non-planar configuration when the VAFN is in the stowed position; a seal retainer defining a seal receiving cavity for the seal; the seal receiving cavity having an arcuate shape extending circumferentially at least partially around the bypass duct; the seal retainer includes a retainer forward flange, a retainer aft flange, and a retainer middle portion extending between the retainer forward and aft flanges; each of the retainer forward and aft flanges extending circumferentially at least partially around the bypass duct and being attached to the forward assembly; the seal located between the VAFN and the retainer middle portion when the VAFN is in the stowed position; wherein the seal includes an outer wall offset from the inner wall and attached to the webs, a plurality of enclosed cell areas being defined within the seal and extending circumferentially at least partially around the bypass duct, the outer wall being attached to the retainer middle portion; characterized in that the inner wall includes a vent port in communication with a first enclosed cell area of the enclosed cell areas; and one of the webs includes a vent port in communication with the first enclosed cell area and a second enclosed cell area of the enclosed cell areas, the first and second enclosed cell areas being different. a forward assembly that defines a bypass duct extending circumferentially at least partially around the engine centerline, the bypass duct being configured to transport bypass airflow of the engine, the forward assembly having an aft edge that extends circumferentially at least partially around the bypass duct; a variable area fan nozzle (VAFN) disposed behind the forward assembly and movable relative to the forward assembly between a stowed position and a deployed position, an upstream bypass flow exit for the bypass duct being defined between the forward assembly and the VAFN when the VAFN is in the deployed position, an outer surface of the VAFN providing an aerodynamic boundary for bypass airflow exited through the bypass flow exit; and a seal attached to the forward assembly, the seal including an inner wall and a plurality of webs attached to the inner wall and extending transversely there-from, each of the webs extending circumferentially at least partially around the bypass duct, the inner wall defining an exposed inner surface that extends circumferentially at least partially around the bypass duct, the inner surface providing a substantially smooth aerodynamic boundary for bypass airflow exited through the bypass flow exit when the VAFN is in the deployed position, at least a portion of the inner surface interfacing with the VAFN outer surface when the VAFN is in the stowed position so as to seal the bypass flow exit, each of the webs having a non-planar configuration when the VAFN is in the stowed position; a seal retainer defining a seal receiving cavity for the seal; the seal receiving cavity having an arcuate shape extending circumferentially at least partially around the bypass duct; the seal retainer includes a retainer forward flange, a retainer aft flange, and a retainer middle portion extending between the retainer forward and aft flanges; each of the retainer forward and aft flanges extending circumferentially at least partially around the bypass duct and being attached to the forward assembly; the seal located between the VAFN and the retainer middle portion when the VAFN is in the stowed position; wherein the seal includes an outer wall offset from the inner wall and attached to the webs, a plurality of enclosed cell areas being defined within the seal and extending circumferentially at least partially around the bypass duct, the outer wall being attached to the retainer middle portion; characterized in that the inner wall includes a vent port in communication with a first enclosed cell area of the enclosed cell areas; and one of the webs includes a vent port in communication with the first enclosed cell area and a second enclosed cell area of the enclosed cell areas, the first and second enclosed cell areas being different.