Geography of Varada

In the Flood of the Apocalypse, Leviathan flooded every plane and world. All was drowning and collapsing into the void of nothingness between planes. But Ostara managed to salvage some worlds as Leviathan's rage was mysteriously quelled. She bound these Seas together, fusing several different planes of water and islands together with shifting, mysterious magic. And so the Seas of Varada were created: vast worlds of oceans, islands, archipelagos, maelstroms, storms and the people who survived to live on them, all connected by shifting magical waterways.

Maelstroms

Throughout every Sea of Varada, there are dozens of Maelstroms large and small. Each one leads to other Seas and dimensions, as they are the doorways to magical realms created by Ostara that bind Varada's shattered Seas together. These strange mystical rivers that flow through the void between the Seas are dangerous but can be traversed, if one has the right ship, charts and a stalwart crew.
In the centuries since the Flood, massive stable Maelstroms have been found that have become central passageways for trade, strategic chokepoints that have been fortified or dangerous hazards that are avoided with care. But the stability and location of many of the myriad smaller ones are constantly in flux. The shifting, unknowable nature of Ostara and the magic that binds Varada together means that there are always smaller Maelstroms opening and closing all over Varada - though only the extremely brave or foolhardy dare to risk traversing them.

The Seas of Varada

The first scholars who attempted to map and catalogue all the Seas of Varada were from the Academy of the Exile's Accord. Those daring explorers risked their lives to build and sail the first ships able to enter a Maelstrom and survive. Many adventurers from the School of Hydrography sailed into Maelstroms only to be lost forever, though their stories and legends live on - especially the ones whose ships were never recovered. This great effort of mapping, traversing and cataloguing took place over two centuries and so eventually the many other peoples of Varada came to trust and rely on the Exile's work to know which Maelstroms were safe and stable. And so the names and numbering of the Seas retains an Exile-centric view.
There are seven major Seas all with stable Maelstrom portals to each other, though the 6th and 7th Seas are rarely travelled or known. However, even the famous hydrographers of the Exile's Accord broadly agree that there may be many other Seas great and small, waiting to be discovered.

The Great Sea (The 1st Sea)

A vast beautiful Sea, teeming with as many islands as there are vast underwater trenches that are said to hold many great Empires of the Deep. The Great Sea is renown for its near constant fair weather skies and bountiful winds, as well as its sheer vastness. This is perhaps both the most charted and at the same time the most unexplored Sea in Varada.
It is also the location of the Eye of Merahl, a massive archipelago that surrounds the flying city of Volaris. This city and the surrounding islands are the birthplace and home to the Exile's Accord. Near to the Eye are two important Maelstroms that lead to the Storm and Emerald Seas.

The Emerald Sea (The 2nd Sea)

The Emerald Sea was named both for its green waters as much as for its primary inhabitants: the Fey.
In the chaos of the Flood, some planes and places managed to hold on to their form and identity and resist their destruction. The largest and most powerful of these was the Feywild itself. Realising the catastrophe that loomed upon them, each Archfey swore fealty and lent their power to one of their own: Venarae, Queen of the Court of Stars. This act not only crowned her as Emperox of a united Fey people and ascended her to Godhood, but it saved the Feywild in one intact piece. Though that realm was now also fused into the material plane and so now it exists as one massive continent that makes up most of the known parts of the Emerald Sea.
Though the coastlines and island of the Fey continent have been charted and mapped, the ethereal and indefinite nature of it's interior remain a mystery to all but the Fey.

The Storm Sea (The 3rd Sea)

The Storm Sea is named both for it's propensity for rough weather but also for the massive Endless Storm that cuts the known parts of the Sea near in half. One tail of the storm always hangs over the Maw: a massive deadly Maelstrom that none have ever traversed and returned to tell the tale. This gargantuan whirlpool causes the currents of the Sea to flow towards and away from it, which has caused many established shipping lanes to be established. For this Sea is known mostly for it's independence and trade. There is a Maelstrom to three other major Seas and so the Storm Sea has become somewhat of a crossroads, a vast territory on a knife-edge of neutrality where hopeful independents resist the pull of Imperial powers.
This Sea is home to The Free City of Elatela, perhaps the largest city in Varada - a haven for trade, commerce and crime. The other major feature is the Moon's Tears Archipelago - a ringed crescent of spiky rocky mountains that has become the sheltered port of Armada, home of the Corsairs and the portal to their Crimson Rivers.
The Storm Sea also has smaller independent communities: The Seven Havens of Yarwind Isle, Death Island, The Fins and Eglirstown.

The Shadowed Sea (The 4th Sea)

So named for the massive area of darkness and shadow that covers both the primary Maelstrom to this Sea and the vast Isle of Blood. The Vampirium of that place found some secret magic in the ancient past to scour the sky and allow themselves to walk in the day and this magic has been expanded to much of the Sea. Beyond the Isle of Blood there is said to be a larger continent of dark forests and cold mountains, but even the most foolish hydrographers have not yet explored that part of the Shadowed Sea.
Despite the name, the Shadowed Sea is not all gloom and darkness. Far to the West of the Isle of Blood lies The Shimmering Coast; a shoreline of glittering cities perched on the edge of a vast desert. These communities are a hub for trade, wealth and science. The main port Al-Surak, is said to rival Elatela for wealth and far surpass it in beauty.
Beyond The Shimmering Coast lies The Emptiness, a vast continent of desert that is theorised to be the ancient remains of the Elemental Plane of Earth, wrought into the material plane. The desert is not lifeless however, the cities on the Coast repeatedly fend off raids from savage warbands that call The Emptiness home. It is also the site of many sacred pilgrimages and expeditions, conducted by the Dwarven people, who have discovered great ruins in the emptiness that hint at their ancient origins. The city of Bhortaruum on the Coast is a major hub for many Dwarven travellers, most of whom come from the Sovereigns' Sea.

The Sovereigns' Sea (The 5th Sea)

Monarchs

Other Seas

The other seas, ideas about 6 and 7.
6 Iron Sea
7 Hidden/Veiled Sea

Also God seas - the Boiling Sea which leads to Aetherion etc. also add an explanation of how spells like plane shift would allow travel between seas but also to those hard to reach places on those plane like the boiling sea.
Link to the Seas Beyond