Zone 19

Zone 19 is a small, lightly-populated freshwater indent off the coast of Zone F. It features a rocky substrate and harsh current.

Meta

As explained by Kemberus, the designer of the original map, Zone 19 came into existence by accident:

lmao zone 16 was a complete mistake i wasnt able to cover the whole thing  because the drawing app i was using had the brush icon over that thing and i could only partially cover it
then the train rocked so my finger slid