The container to hold liquids to be carried through the air and the container to hold air to be floated upon the water are the same word.  In these two uses, the former meaning applies.

• 12.014 and vessels filled with a wealth that could not be guessed.
• 14.011 Every vessel

“vessel, n.1.” OED Online. Oxford University Press, June 2016. Web. 4 July 2016.