Abstract: A cooler insert partition is provided for a container having a hard-walled internal chamber surface. The partition has a spanning matrix and a peripherally extensive margin that defines a dimensionally variable boundary that follows the tapered chamber wall, functions as a wiper, and is deformable in at least one of (a) in-plane compression; and (b) out-of-plane deflection. The margin forms an edge of the spanning matrix. The partition is insulated, and is softer and more flexible than the hard-walled chamber surface. The periphery is thinner in cross-section than the spanning matrix and has a smaller specific flexural modulus. The partition has articulated panel sections. The partition is made from a single polymeric monolith that has been cut and formed. In use the partition is progressively re-positioned in the chamber to minimize dead air space as container contents are removed.