A drinking vessel includes an outer vessel, a deformable retaining flange, and a removable insert structure formed of glass and configured to be disposed within the outer vessel. The insert structure may have a sipping portion configured to extend out of the open end of the outer vessel and the deformable retaining flange is configured to releasably retain the insert structure within the outer vessel.

A flask has an insulated outer container having an upper opening and an inner container having an upper opening. The flask has a lid that is configured to removably attach to the outer container and to form a substantially watertight seal with the outer container The inner container is slidably and removably housed within the outer container.