I heard on TV (an American science program, forgot the name of the program):
We will venture out into the farthest reaches of the cosmos.
It makes me wonder if/when the noun "reach" is a count noun and can be pluralized. Bizarrely, according to Macmillan Dictionary and Cambridge Dictionary, it is either a noncount noun or a singular noun.
Google shows both terms are in use. For example, there is a book called Farthest Reach, but also instances of books and songs by the title (the) Farthest Reaches abound.
Google Ngram shows something interesting. The popularity of these two terms has changed over time:
So is reach also a count noun? And when should it be pluralized?