Sea of Fallen Stars

The Sea of Fallen Stars, also known as the Inner Sea, was the largest inland body of water in Faerûn. Its major areas included the Dragonmere, also known as the Lake of Dragons, in the west; the Dragon and Easting Reaches in the north; the Alamber Sea in the east; and the Vilhon Reach in the south.

The sea served as a crucial trade way for the powers of central and northern Faerûn and beyond. From Cormyr's Imperial Navy and Sembia's 15,000 sailors and corsairs in the west, to the small but hardy fleet of dozen Impilturan warships in the east, and the militia-navy of Turmish in the south, the waters of the Inner Sea were well-traveled by ships that flew the flags of coastal nations in central Faerûn.

Description
The sea floor was covered with hundreds of shipwrecks.

Inhabitants
The Inner Sea was home to many types of aquatic life, and including kingdoms of dragon turtles, aquatic elves, merfolk, and sahuagin. With the exception of a notable violent excursion in 1369 DR, these races rarely interacted with the coastal land folk.

Territorial Waters
There was a recognized territorial limit of ten miles (16.1 kilometers) offshore among all the nations on the Sea of Fallen Stars. Areas of sea further than ten miles from the nearest land were considered neutral territory. Any attacks on shipping within a country's waters were considered to be acts of war. For most areas, these boundaries were clear, but they became more ambiguous in Mulhorand, Thay, and Unther, owing to continual border disputes.

Creation
Over the millennia, different creation myths regarding the sea spread across the Realms. One tale, which explained how the sea earned its name, was detailed in the book History of the Last March of the Giants. It said that the gods above sent a star crashing down to Abeir-Toril as a punishment for the arrogance of the titans. Entire continents were lost in the ensuing earthquakes, fires, and windstorms and the four centrally located seas of Faerûn merged together, forming the "Sea of Fallen Stars".

Other theories maintained the cataclysmic change of landscape was actually the eggs of the first dragons raining down onto Toril.

The true creation of the sea occurred ages ago, in the final years of the Days of Thunder, when the primordial Asgoroth the World Shaper, along with the first dragons, were released from their imprisonment by the creator race known as the batrachi. In an event known as the Tearfall, the deity hurled an ice moon down to the surface of Abeir-Toril, which wiped out the batrachi and formed the sea.

Sarrukh accounts dated around mentioned a "changing of the stars" in relation to this event. Few knew what this really signified, but the fact was Ao created a duplicate of the planet, Abeir, and sent the new world to another realm, with different stellar cartography.

Spellplague
On Tarsakh 29 1385 DR, the Spellplague hit Toril and greatly changed the landscape of the planet. Large openings erupted within the Underdark and large portions of the sea drained out beneath Toril's surface, greatly lowering the sea level over the next ten years. Coastal cities that once rested on the banks of the sea were made land-locked, and formerly submerged ruins and wrecks were subsequently exposed. One of such resurfaced islands was Hegruth, an Island with a tower that's been submerged in the Sea of Fallen Stars for millennia. The tower ruin of unknown origin and obscurity made it the perfect place for clandestine meetings. The island did not appear on any terrestrial maps.

The Second Sundering and the Great Rain
During the Second Sundering in the autumn of 1485 DR, the Great Rain began to fall around the Sea of Fallen Stars and continued unceasingly for over a year. This constant storm caused massive floods; thousands perished from drowning, lightning strikes, or bursts of wind that capsized ships. By the time the rain abated, the Sea of Fallen Stars had swollen back to something approximating its former size, flooding vast tracts of land and numerous cities beneath the waves.

Islands
There were numerous islands in the Sea of Fallen Stars:
 * Alaor: A former Thayan island that gained its autonomy.
 * Pirate Isles: A group of about sixty rocky islands notable as the home of the pirates of the Inner Sea.
 * Isles of Prespur: A main island under Sembian control accompanied by the smaller unoccupied Traitor's Isle.
 * Ship of the Gods: An island volcano in the Alamber Sea.
 * Whamite Isles: A small chain of islands once ruled by a great khan.
 * Hegruth (an Island with a tower, surfaced due to receded water levels circa 1396 DR)

Undersea

 * Myth Nantar:
 * Serôs: The underwater realm of the merfolk, who were protected by the Nantari dukar.
 * Xxiphu:

Coastal
The Sea of Fallen Stars had coastlines in many different lands, including Aglarond, Altumbel, Cormyr, Chessenta, Chondath, the Dalelands, Impiltur, Sembia, Mulhorand, Priador, Thay, Thesk, Turmish, Unther, and the Vast.