Does Mars' "Northern ocean" have another name? What about the "Inland Sea"?
According to the Wikipedia article on the Mars ocean hypothesis, the ocean is sometimes called the Paleo-Ocean, and sometimes called "Oceanus Borealis" (a.k.a. "Northern Ocean" for those who feel that quidquid Latine dictum sit, altum videtur.)

The inland sea in the article is located in the Simud Interior Basin (part of the Simud Valles). The Nature article describing the findings (Rodriguez et al. 2019) doesn't appear to give the sea a name, although it does use the term "SIB sea" at one point.