"In parts unknown" is a phrase used to describe a location that is unfamiliar or unknown. However, there are many synonyms for this phrase. Some of the commonly used synonyms include "in a remote location", "in an isolated area", "off the beaten path", and "in uncharted territory". Other synonyms can include "in a distant place", "in a far-off land", or even "in the wilds". These words can be used in various contexts, including when describing travel destinations, exploring new territory, or simply referring to a place that is hard to reach or unfamiliar. So, if you're looking for an alternative to "in parts unknown", these words can help you get your point across.