Walk Any Road, Float Any River (Third River Freedom)
This freedom implies no safety while traveling, especially from the local lord. It merely prevents lords from blocking land and water travel, or charging tolls for passing (except for non-Riverfolk). Of course, any ruler who doesn’t want people on his roads can bar them without erecting a single block - threats, bribes, political pressure, or hiring “bandits” are just as effective.
However, in practice, it means no lord can take his or her people for granted. Most Riverfolk do not leave their homes for anything but essential travel, no matter who is in charge (and poor Riverfolk usually have nowhere else to go), but they might still move to a new kingdom if their lord is abusive. This escape is rarely necessary. A lord who wants a functioning kingdom knows not to treat subjects too harshly, or the best ones will disappear, leaving a half-empty kingdom behind.