Abstract: A reusable insulated flexible cooler bag comprising: a front wall having a first inner layer, at least one first insulating layer, and a first outer layer of plastic material; a rear wall having a second inner layer, at least one second insulating layer, and a second outer layer of plastic material; and a closure element. The front wall and the rear wall are joined together at their peripheral edges so as to create a pocket-like configuration with an inner volume. The closure element is able to close the pocket-like configuration to substantially ensure an airtight and watertight seal of the inner volume of the reusable insulated flexible cooler bag and is located adjacent a top side of the reusable insulated flexible cooler bag in order to provide access to contents of the reusable insulated flexible cooler bag.