The present invention is a cooling device having a number of cooling sub-assemblies, each having a body having a top with an opening, and an interior chamber for holding a cooling fluid. An equal number of sub-assembly connectors connect each body to two adjacent bodies so that the cooling device forms a generally cylindrical inner surface that can be placed around the outside of a beverage container so cooling fluid can absorb heat from a beverage in the container. Each sub-assembly may also have an activator bin inside it for storing an endothermic reactant and having a release mechanism that a user can activate to cause the endothermic reactant to mix with the cooling fluid thereby cooling the cooling fluid which in turn cools the beverage.