There are five commonly recognized seas in Patrocia today:

The Sea of Iron
The Seas of Zanthos
The Frostborne Sea
The Forsaken Sea
The Sea of Corsino

All are dangerous, none are fully known.

The Sea of Iron

A name used for the seas South of the Old World, the Sea of Iron used to be called the Silver Sea back in the day, but ever since the Rhodesian successor wars it has been a place of conflict and strife so great that its current name came into use. It is an excellent place to find salvage and riches if you have the skill and nerve to claim it.

If you choose to brave the Iron Sea, in addition to the regular beasts and hazards of the seas you should prepare to potentially encounter:

The Undertow Corsairs

This band of ne'er do wells is a persistent threat in the Sea of Iron. Originally a loosely organized group looters and salvagers combing old battlefields, the eventually salvaged enough weaponry from sunken warships that they decide to stop waiting until ships sunk to take everything that wasn't nailed down. They're an unpredictable bunch of reprobates who will gladly rob you blind and leave you to row back to port in a life boat. They practically live aboard their ships, but rumors do persist that they must have a smugglers port somewhere.

The Free Raiders

Silas Rooke was a captain in the Royal Hateshian Navy who served with distinction in over 15 years of war at sea. When his commanding officer finally retired, Rooke was passed over for promotion and an entirely unqualified noble's son was given the post instead. Rooke was aghast, but honored his duty. When that noble's son turned out to be wildly incompetent and corrupt, Rooke still honored his duty. But when this commander ordered him to keelhaul his first mate for speaking out of turn to object to the suicidal orders they were being given, something in Rooke snapped.
He keelhauled the commander instead, deserting with his men and beginning a campaign of vengeance against anyone and everyone who served any kind of nobility.

From his ship, The Drowned Cur, Captain Rooke has grown his cause and now commands a fleet of deserter ships that will ambush lone vessels, slay all aboard who don't desert to join them, and either commandeer the ship or send it to the bottom of the ocean.

The 1st Hateshian Fleet

Led by Vice Admiral Skala Baro aboard the IHN Imperious, this fleet has seen many conflicts.
Their standing duty is to hunt enemies of the emperor but they are free to interpret this creatively as the situation requires. For example, are you a merchant passing through their waters? This group might seize and search your vessel for "enemies of the emperor" without much fanfare. After some interrogation and maybe a small tax for wasting their time, you'll be allowed to continue your journey. The problem comes if you fly the flag of a nation not allied to Hatesh, or fail to fly a flag at all. At that point you're likely to become target practice for the gunners of these imposing warships.

The 3rd Fleet of Michino

Michino's answer to the 1st Hateshan Fleet, the 3rd Fleet is led by Vice Admiral Sebastian Di Carrow from the IFM Swift Accord. Performing much the same functions as their rival, the 1st fleet, the 3rd is assigned to guard the southern coast of Michino from threats. While this ostensibly means pirates and deserters, the 3rd fleet skirmishes with the 1st fleet with some regularity. In fact, the two fleets have been at each other's throats for almost a full 70 years now, with varying levels of intensity over the years. The rivalry between the two most recent leaders is so well known at this point, they're sometimes collectively referred to as The Dueling Vices.

The Sea of Zanthos

This much more peaceful sea is used primarily by explorers and traders looking to use the Harbinger Strait to avoid the worst of the conflict in the Sea of Iron on their way to Michino or its allied states. Named for the beast legend say resides in its waters, the sea is less travelled than you might expect due to overland trade being generally safer.

The Antinian Triumvirate has little investment in the sea beyond trade fleets and The Imperial Fleet of Michino maintains a token force to protect its border. As a result, much of the traffic is coastal.

If you attempt to reach truly far out East you'll encounter winds that very consistently blow towards the mainland, as well as currents that would send you in circles if you tried to row, so much of the distant waters are quite sparse in travelers.

If you do manage to get past this natural roadblock, strange things have been reported in the waters. An island once charted may have vanished, and new ones appear where none were before. Collectively these are known as the ghostly isles and they're an iconic phenomenon in these seas. Once or twice an outlaw or pirate has sought to harness the usefulness of on of these isles for a base that is hard to find, but once they set out and stake their claim on a vanishing isle they're almost never seen again. Those that do return speak of a sunless sky and a great sea beast that legend has seen fit to call Zanthos.

The Treasure Fleets of Antinia

Antinia is a nation rife with banks and bankers, and their fleets are thusly rich with spoils of their trade. Antinia is no stranger to this reputation however and consequently their fleets are also rich with cannons and ships. Just a single vault-ship can carry enough wealth to ensure a captain a whole fleet of his own ships, but a vault-ship is a daunting prospect. For one, as it's name suggests, it has a considerable amount of security on board. Even if you get on board and into the hold, the compartment the treasure is stored in is a literal vault to which none but the sender and the receiver of the shipment have the key.

What's more, vault-ships travel with an escort of no less than three other ships, all bristling with weapons and armed marines happy to earn their pay reminding ambitious pirates why they're so well compensated.

Naturally this means that attacks on the treasure fleets are rare, and if successful they almost certainly involved a painstaking web of intrigue and multiple captains working together for their share of the spoils. Far more often the high stakes and higher payouts tend to fracture the tenuous alliance of pirates shortly after the vault-ship is taken and the whole thing falls apart due to greed.

If you hope to sample the riches of Antinia, you'll need a small fleet, captained by people you'd trust with your life, and a way to compromise some of the most powerful people in Antinia. History has shown that still may not be enough, so good luck!

The 6th Fleet of Michino

Often considered a sleepy post, the 6th fleet is home to many political outcasts and dead enders on the last stop of their military career. A sailor punished with this posting can look forward to days of sailing around aimlessly and maybe hunting the occasional pirate. Few threats to Michino come by this way, so the fleet itself isn't overly large.

The 6th fleet is led by Rear Admiral Vincent Impago aboard the Curious Fate, sometimes called the Listless Fate much to it's captain's chagrin. Rear Admiral Impago hasn't seemed to realize his career is over yet and does his best to continue enforcing military discipline on his troops who are more clued into their working retirement than he is.

The Three Rings Smugglers

Helped in part by the disinterest of many sailors working to patrol these sleepy waters, the Three Rings are an organized crime group who often move their goods via these waters. They tend to stay far away from treasure fleets and patrols, but it's hard to argue their job is difficult when they're away from port.

Their leader isn't known for obvious reasons, but some suspect they have ties to Antinia.

Zanthos

I know, I know, it's fanciful to add this here but it's worth considering.
Zanthos is reported to be something akin to a massive proto-lobster of some kind. It's rumored to have claws the size of a corvette, and armored plates thick as a frigates hull. It lurks in the far off places of the sea that bears its name, but occasionally ventures closer to the shore.

This beast is very rare to encounter, maybe only once a year or less, but it is feared in large part because of it's unpredictability. Much like its much smaller lobster relatives, Zanthos eats whatever it can get its hands on. If you're lucky, its appetite is sated and it will just watch you with passing interest. If you're unlucky, the shipwreck you hope to plunder was sunk by Zanthos and the beast is still in the area and looking for more.

If you ever see its massive tail breach the water, or hear it's echoing almost metallic cry, turn away from the sighting and start praying it hasn't noticed you yet.

The Frostborne Sea

This is a somewhat harrowing sea to travel. As the name suggests, it's a colder climate with freezing winds getting worse as you venture farther north. Unlike with the New World there are no ocean currents bringing warm water this way and keeping the land temperate, the islands here will be desolate places. What's more, the most well-known local inhabitants are fearsome folk known as Bone Raiders. As a result there is very little mapping and exploration of this sea for a traveler to consult for their journey. If you have the connections, I would advise talking with House Duran for their charts if you intend to seek anything out here.

The Bone Raiders

It's impossible to discuss the Frostborne Sea without encountering talk of the Bone Raiders. These ancient foes of Patrocia's shores have been sacking coastal settlements and attacking ships since before Valkorian the Great united the Old World. When House Duran were created by the Iron-Gold Mandate, they drove them back to this sea, where they have lurked ever since. They are a warriors who sail ships reenforced with the bones of sea monsters they hunt, they appear, strike, and vanish with speed and precision, taking prisoners who are never seen again. No one has seen a Bone Raider settlement and lived to tell the tale, so their culture is still a matter of speculation and myth.

In particular though, I would leave you with a warning to avoid any Bone Raider ship with crimson sails. Dark magics lurk aboard those ships, and the dead serve the captains with unbreathing endurance.
Turn away unless you are ready to fight horrors and withstand the cursed onslaught of a necromancer's wrath.

House Duran

The preeminent masters of charting the seas and safeguarding the Old World from threats abroad. House Duran have the largest private navy in Patrocia, and they make good use of it exploring, charting, and naturally, escorting other ships for pay. They're expensive, but they're a great way to make sure you make it to wherever you're going in peace.

The Harbian Navy

The Tsardom is a seagoing power many underestimate. Their navy has a strong presence in the northern waters of Patrocia and the Harbinger Strait. Their ships are low to the water with strong hulls and sometimes even innovations and experimental weapons gleaned from their Tsar's ample patronage of House Vincelli. They usually leave other vessels alone unless they bear flags from Hatesh, Michino, Vitan, or are clearly Pirates. They often aid House Duran in combatting the threat of the Bone Raiders. The rest of Patrocia may have forgotten, but Harbia were the first to fight them, and should they return to their old strength unchecked, Harbia would be the first to fall.

The Iceblooded Peoples

Not Bone Raiders, but a people who live somewhere in the Frostborne Sea. Contact with them is quite rare, as they are an insular people with little interest in trade. They are reportedly stoic, but wary of outsiders. They are unlikely to cause you trouble, but may be a valuable source of information if you can find something worthwhile to offer them in trade.

Pirates of the Northern Waters

Pirates are a constant presence throughout the all the seas. In the North you'll find pirates such as Captain Benvolio Matias aboard the Chill Wind, famous for his speed and tenacity. Or perhaps Captain Christina "The Nightshade" Walker, who is as beautiful as she is deadly aboard the Lady Luck. Lastly, you might run into Ulfgar Fairhair, a berserker if there ever was one, captaining his vessel The Bloody Axe. There are always up and coming pirates too, so watch your back out there even if it's not someone whose reputation precedes them.

The Forsaken Sea

Here be monsters, and those who hunt them. This is one of the more dangerous regions in Patrocia, not for what's on the water but for what lurks beneath it. Most of the people who do travel this region are from the New World or headed towards it.

The Teeth of Jagara

These prolific monster hunters are native to the New World, sailing out to fight the great beasts of their southern ocean as part of their cultural rite of passage. While there is still much that is traditional about their hunts, they do not shirk modern weaponry. Their vessels have similarly seen great strides since our first contact with them. If you seek a beast of your own, you would do well to seek them out for aid tracking or hunting.

If you find yourself in their waters, offer them a sufficiently strong proof of your status as a monster hunter in the form of a trophy from a great beast and they may also be a valuable source of trade or offer a port to repair.

The Rypherron

These beasts are Octopoids with 8 mighty arms, rivaling a giant squid for their colossal size. Generally only seen in the Forsaken Sea, they're particularly dangerous because of their habit of ripping ships apart and then using a vanquished ship's hull as a shell of sorts. This makes shipwrecks a dangerous thing to investigate in these waters.

The Wake-Singers

These curious creatures are one of the few beasts of their size you won't be scared to see swimming towards your ship. Travelling in pods of 3-5, these man-sized eels are scavengers who follow ships and feed off the barnacles on the hulls and scraps thrown overboard by appreciative sailors. They sing to communicate, I'm told they sound ethereal but beautiful at the same time. When their sails breach the water's surface don't be surprised when the sailors start singing back to them in belief it brings good luck.

The Dread

This beast is so named for its nasty habit of stalking ships for days before striking, it's large dorsal fin is sometimes mistaken for a far-off ship's sail. This massive shark-like fish is very skittish, but far more powerful than its behavior would indicate. They are considered very difficult to hunt as a result.

Spirit Sirens

When the night is dark and you're alone on watch, you may spot the soft glow of a human shape that beckons in the darkness. I tell you this with utmost certainty and grave import: Do not go to this light. It is the lure of a vile angler fish with a long tongue and row upon row of dagger-like teeth. It will lash its tongue at a sailor who approaches the edge of the ship and drag him into a painful death.

The Sea of Corsino

House Gautier

The merchant ships of House Gautier are a common sight in these waters, and are an excellent source of trade and supplies should you need it. Don't get any ideas though, they're still very well armed for being trade vessels.

Pirates of the Central Sea

Due to the riches that travel the shortest route between the Old World and the New World, pirates are amply incentivized to ply their trade.

Notable captains include:

• Captain William Gaunt aboard his frigate The Wily Baron, he's a master of the hit and run.
• Captain Esmerelda Vale, sailing her Brig The Contessa's Vengeance. Her skills with a blade are the thing of legend, don't let her board your ship if you value your cargo.
• Captain Stricio Elderbaden, who trades blows with the best of them on his man-o-war The Last Laugh. A trading broadsides with him would be a costly mistake, best to run unless you're sure you can win.

But aside from them there are still plenty of other pirates who may surprise you, keep your head on swivel!

Colony Ships

The Old World colonial powers send ships to their colonies full of supplies and colonists.. These ships themselves aren't overly armed, but they're seldom without an escort.

Treasure Fleets

While Colony ships ferry supplies and manpower, all colonial powers plunder the new world and arrange ship convoys to bring their riches home. These purpose-built ships are defensively strong to deter pirates, but that seldom actually does.

The Ashfury Reavers

These are no pirates, pirates will parley when you fly the white flag. The Ashfury Reavers hold no value towards a life that isn't one of their own. It's not clear where they sail from, but they do not leave survivors when they strike and they won't ally when anyone, not even the Vitan Federation. If you spot a ship in flames, it's likely one of their latest victims.