Sea of Fallen Stars
The Inner Sea was once four separate bodies of water until the batrachi realm of Kolophoon was devastated nearly 33,000 years ago. Scholars generally hold that a chunk of Toril’s second moon struck Faerûn at that time. Today the Sea of Fallen Stars has dropped almost 50 feet from its pre-Spellplague level.
The Abolethic Sovereignty, ruled by aboleths and their aberrant servitors from its floating city Xxiphu, is greatly feared throughout the region. Other monsters known as the Unfettered swim the waters and soar the skies of the Sea of Fallen Stars.
The undersea depths of Serôs are controlled in the west by fey from Myth Nantar and in the east by the sahuagin realm of Aleaxtis.
The Pirate Isles host buccaneers, cut-throats, and the like, though pirate attacks have been significantly reduced in the last century.