On the official map of Equestria, there is a location called Horseshoe Bay. See Locations. Baltimare is located on the shoe of Horseshoe Bay, according to the map of Equestria featured in the "Locations" article.
Horseshoe Bay is featured in the comic-book story arc My Little Pirate: Friendship Ahoy and in the Daring Do story Daring Do and the Eternal Flower.
Will Horseshoe Bay appear in Season Six of My Little Pony Friendship is Magic? I hope so.
I kind of envision Horseshoe Bay as one of the more lawless and chaotic areas of the pony kingdom/nation.