uncharted water

== English == === Noun === uncharted water (countable and uncountable, plural uncharted waters) An area of sea that has not been surveyed, or whose details have not been entered on nautical charts. Near-synonym: abyss (figuratively, usually in the plural) Any unknown and potentially dangerous situation. Synonyms: uncharted territory, terra incognita Coordinate term: terra firma (often antonymous to this sense)