Abstract: An improved vent unit for a container such as a bottle, and a bottle assembly utilizing same. The vent unit includes a vent insert having an upper portion capable of sealingly engaging an opening in an upper region of the container and having a lower portion including a vent tube communicating with the atmosphere through at least one air passage in the upper portion. The upper portion defines at least one channel for liquid in the container to flow past the opening in the container. The vent unit also includes a vent conduit having upper and lower ends and defining a vent passage there-between. The upper end of the vent conduit is connectable with the vent insert to communicate with the vent tube, and at least a portion of the vent conduit is flexible. At least one buoyant element is associated with the vent conduit to enable the lower end of the vent conduit to float in liquid within the container at least when the container is realigned from a vertical position to a horizontal position.