The Federation of Bosnia and Herzegovina is one of the two entities within the State of Bosnia and Herzegovina. Again, if you did not understand it the first time: the Federation B&H is part of B&H. It's a result of the war, of ethnic dominance and ethnic killings. There is nothing logical about the whole situation. Let us be glad that at least there is no war at the moment.
The Federation of Bosnia and Herzegovina is part of the Dinarides and heavily karstified. There is a watershed, and despite being so close to the Mediterranen Sea most of the region actually drains to the Black Sea. The region has numerous exceptional karst feature and great caves. The Trebišnjica is one of the longest sinking rivers in the world. It belongs to the Adriatic Sea drainage basin.