WordNet records no synonym and no antonym for continental divide. It is the only member of its synset, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
the watershed of a continent (especially the watershed of North America formed by a series of mountain ridges extending from Alaska to Mexico)
Synonyms, antonyms and the broader and narrower relations for continental divide come from Princeton University’s WordNet. Full sources and licences.