And now for something rather…different.

This is a map of Serôs, the underwater realms of the Sea of Fallen Stars, in the Forgotten Realms world. We previously mapped the overland continent of Faerûn here, but Serôs is the hidden world in the centre of Faerûn, a land of warring kingdoms, ruined temples, dark dungeons and ferocious monsters, all lying underwater.

A Map of the Undersea Realms. Please click for a larger version.

The Surface Waters

The Sea of Fallen Stars, also commonly called the Inner Sea, measures approximately 846,774 square miles (2,589,999 km²) in area. Located in the north-central area of Faerûn, it dominates the centre of the continent and provides an inlet for many of the rivers and lakes of the continent. The Inner Sea is connected to the outer oceans – the Trackless Sea and Great Sea – via underwater tunnels located many thousands of feet below the surface, providing an outflow for the otherwise landlocked body. Civilisation, certainly human civilisation, began on its shores with the early human empire of Imaskar extending along its eastern edges, whilst modern nations around the sea owe their founding to the ancient kingdoms of Mulhorand and Chondath. Today, the Sea of Fallen Stars is Faerûn’s most important waterway, providing both trade and rapid transit across the centre of the continent.

On the surface, the Sea of Fallen Stars is divided into several distinct areas: the Lake of Dragons or Dragonmere lies at its far western end, connected to the rest of the sea by the narrow channel known as the Neck. The Lake of Dragons is relatively shallow and is notable for the peaks of the Storm Horns rising to the north-west and the plains of the Horse Prairie to the south. Due north lies the powerful kingdom of Cormyr.

Immediately to the east, the Inner Sea expands into a wide gulf between the nation of Sembia to the north and an array of city-states to the south, the most powerful and notable of which is Westgate. The Isle of Prespur, which is divided into a Cormyrean and a Sembian area, lies at the eastern end of this stretch of water.

To the north, the sea enters the Dragon Reach, which divides Sembia and the Dalelands from the Vast. The shores of this gulf are dotted with notable city-states, including Port Scardale, Calaunt, Tantras, Ravens Bluff and Procampu. The River Lis connects to the Dragon Reach to the Moonsea to the north.

The central area of the sea is dominated by the forbidding Pirate Isles of the Fallen Stars (to differentiate them from the Pirate Isles of the Trackless Sea, also called the Nelanther). The Pirate Isles are, as the name suggests, home to several significant pirate fleets and groups. The other nations periodically clear out the isles, but the pirate scourge always returns.

Easting Reach is the north-eastern-most arm of the sea, and divides the kingdom of Impiltur in the west from the Great Dale and the nation of Thesk to the east. To the south, the Easting Reach turns into the Sea of Dlurg, which divides Thesk from the nation of Aglarond to the south-west.

The Vilhon Reach lies to the south-west and is the newest of the sea’s “arms,” being created in 255 BDR (Before Dalereckoning) by the destruction of the empire of Jhaamdath at the hands of elven High Magic. The modern nations of Chondath and Sespech hold shores along the Vilhon, whilst the nation of Turmish to the north extends to within a few miles of its shores. Independent city-states like Reth, Hlath, Nimpeth, Hlondeth and Torl dot its shores.

The Wizards’ Reach in the south-east divides the independent city-states of the north coast (of which Laothkund is the most powerful) from the nation of Chessenta to the south. The Reach opens into the Alamber Sea, sometimes called the Sahuagin Sea, which divides Threskel and Unther in the west from Mulhorand in the east and Thay in the north. The Alamber Sea is arguably the most dangerous part of the Inner Sea, with the volcanic island known as the Ship of the Gods constantly threatening to erupt and the hostile, powerful empires of Mulhorand, Unther and Thay constantly engaged in tensions and intrigue.

The Undersea Realms

However, below the surface lies a very different world. The natives call the Sea of Fallen Stars Serôs, a merfolk term meaning “The Embracing Life,” and it is an interesting and strange world where length and breadth is joined by a new direction: depth. The Inner Sea’s floor sits approximately 1,500 feet (457 metres) below sea level, but several trenches and undersea cave systems drop immeasurably further than that. The depths of the trenches are believed to exceed 2500 feet (733m) and connect to the Underdark and, some believe, the Glimmersea, the immense Underdark ocean lying a full twenty miles (105,600 feet, or 32,187m!) below the floor of the Inner Sea.

Those extremes are rarely travelled, however. In everyday life in Seros, the depths are divided into six approximate levels: the Shallows (0-150 feet/0-45m), the Gloom (151-300 feet/46-91m), the Twilight (301-600 feet/92-183m), the Upper Depths (601-1200 feet/184-366m), the Lower Depths (1201-2400 feet/367-732m) and the Underdeep (below 2401 feet/733m), with most civilisation clustering around the upper levels.

As well as by depth, Serôs is divided horizontally between several notable nations, as well as various open areas unclaimed by any polity.

As’arem or the Empire of Arem dominates the north-east of Serôs and is controlled by the shalarin, a (mostly) friendly undersea race. As’aren is divided between four lesser kingdoms, named Es’rath, Es’daan, Es’purr and Es’roch, with the empire’s overall capital located at the city of Us’rath.

Eadraal is the most famous nation in Serôs and arguably has the closest ties to the surface world. Eadraal is dominated and mostly controlled by the merfolk, but they are unusually tolerant and a large number of other races live in their domain, including shalarin, sea elves, tritons and a surprisingly large number of surface dwellers, surviving in the ocean depths with magical or technological aid. Eadraal is arguably the most powerful kingdom of Serôs, expanding around the Hmur Plateau (the undersea plains from which rise the Pirate Isles) as far north-west as Duna’s Kelp Forest. It has an administrative capital, Voalidru, although its most famous settlement is the semi-independent city-state of Myth Nantar, the centre of trade and commerce in Serôs.

The Triton Protectorates surround the Trench of Lopok and consist of three powerful triton city-states (Vuuvaxath, Ahlorsath and Pumanath), aligned with one another and with the Myth Nantar alliance for trade and mutual protection.

Olleth, south of Myth Nantar, is the undersea kingdom of the morkoth, noted for its impressive magical power. The Ollethi are somewhat distrusted and even feared by the other undersea races for their magical powers, but they are heavily outnumbered by the other Serôs nations, which keeps their ambitions in check.

The ixixachitl nation of the Xedran Reefs lies along the coast of Turmish and is noted for its occasional hostility towards the other nations of Serôs, although their ambitions have not so far extended into open warfare.

The sea elven kingdom of Selu’maraar lies along the floor of the Dragon Reach and is noted for its isolationism. The Coronal of Aluwand sees the other undersea nations of Serôs as potential rivals and enemies, and he prefers to keep his borders closed. However, other sea elves believe that Selu’maraar’s destiny lies in greater contact with the rest of Serôs.

Naramyr is another sea elven kingdom located in the relatively shallow Lake of Dragons. Naramyr enjoys friendly relations with the surface human kingdom of Cormyr, and there is an unusually high level of trade between the two nations (their capitals of Telvanlu and Suzail are also quite close together). Naramyr’s presence is useful in that the sea elves recover many survivors of shipwrecks on the lake and convey the survivors to the coast of Cormyr.

The Lost Lands lie between Naramyr and Eadraal and consist of a wide swathe of unclaimed territory, divided between bickering koalinth tribes like the Severed Fins and Kraken’s Rage. The sunken Netherese flying city of Sakkors is still rumoured to lie on the sea floor, somewhere west of the Haunted Plains.

The Selmal Basin, known on the surface as the Vilhon Reach, is the shattered remnant of the ancient sea elven empire of Aryselmalyr. Despite the passage of almost 1,500 years since that cataclysmic event, the sea floor is still littered with the ruins of the empire and is shunned by sea elves. The basin is today inhabited mostly by koalinths.

To the east of Eadraal, Olleth and the Triton Protectorates lies the Sharksbane Wall, an immense fortification built atop Hunter’s Ridge. The wall was constructed at the height of the Aryselmalyr Empire to defend against sahuagin attacks from the east. The Wall is 137 miles long and extends to within 100 feet of the surface, and is patrolled by sea elves, occasionally joined by other races. The wall cannot stop small bands of sahuagin passing over, but it does prevent any large-scale assault.

The Sharksbane Wall was breached by the armies of Iakhovas the Taker during the Twelfth Serôs War. The rest of the Wall remains intact, and patrols around the breach have been reinforced.

East of the Sharksbane Wall lies the sahuagin kingdom of Kurrimal, with its capital at T’Kalah, located in the Alamber Sea near the Alaor. Kurrimal’s territory is contiguous with that of the merrow kingdom of Poragga. The merrow control the shallows down to 300 feet below the surface, whilst the sahuagin control the depths from there down to the ocean floor. The sahuagin of the Wizards’ Reach and Alamber Sea are the most constant threat to the rest of Serôs, but they suffered grievous losses in the Twelfth Serôs War and an eruption of the Ship of the Gods volcano which destroyed much of their south-eastern-most lands.


The most detailed information on the underwater realms of the Inner Sea comes from the 1999 book, Sea of Fallen Stars by Steven E. Schend. Mel Odom’s Threat from the Sea novel trilogy expands on the sourcebook.

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