According to tradition, which alcoholic beverage should always be passed to the left (clockwise)?

Tradition dictates that the Port decanter should be placed on the table to the right of the host or hostess. It is then passed to the left, going clockwise around the table until it comes to rest at its starting point.

Port is never passed across the table or back on itself – it’s only to the left. There are several theories as to why this is:

Historically, to keep one’s sword arm free
In the Royal Navy, the rule was ‘port to port’, i.e. ‘all the way around’
To simply ensure it’s shared fairly and no one misses out