Seventh Sea

The Seventh Sea

Many planes have seas, but if a cutter sails far enough they may sometimes find themselves completely lost. This, in fact, is the Seventh Sea planar pathway; a state of being so far from land in any direction that any way is effectively the same. Remember, cutter, that the Outer Planes (bar a couple of weird ones) don’t have stars or compass points to direct a lost sailor.

When you’re this lost, it’s the hopes and expectations of the ship’s crew that guide the vessel through the Seventh Sea of the Astral and to the destination the crew most want to reach.

What is the Seventh Sea?

When the soul of a freshly-deceased berk departs from the Prime on its journey to the Outer Planes, it first must pass through an astral conduit — an intangible and invisible vortex, that leads through Astral Plane. As souls pass through such conduits, their memories are stripped away and condensed into memory cores. These look like a small and fragile spheres, metallic in color. When a spellcaster casts speak with dead, they in fact communicate with this core—not with the actual petitioner themselves, since they’re reborn without memories in the Underlands after they reach the Outer Planes.

But memory cores do not last forever. As they jostle around on the Astral and are unlocked by divination and necromantic magics, they slowly erode and after many centuries evaporate completely. But evaporate doesn’t mean disappear. Invisible tiny fragments of all memories creatures had in their lives condense at the metaphorical bottom of the Astral Plane. This is the Seventh Sea, the great uncharted planar pathway between all planar seas.

Conditions

The Seventh Sea may be made from condensed memories, but physically it behaves just like water—so long as it remains on the Astral. You can drink this water, but it doesn’t help with thirst (if you even manage to find a place on Astral where you can experience thirst). Astral pseudo-water still responds to spells that manipulate regular water. However, once taken out of Astral, the condensed memories instantly dissipate.

The Seventh Sea flows through the Astral and it shares many similarities with it. Sailors of the Sea do not need to breathe (even underwater), eat, drink or sleep. They don’t age on the plane itself, but time catches up with them upon leaving. The memory water of the Sea creates its own gravity. Fortunately, due to the way Astral travel works, it’s highly unlikely that a body will stumble upon the Sea accidentally. Whilke there’s a surface, most graybeards believe that the Silver Sea stretches infinitely downwards, having no bottom.

Like elsewhere in the Astral, movement in the Silver Sea is dependent on the mind [Intelligence score]. It represents sheer mental power that’s able to propel a thinking creature. Many ships that sail the Sea employ magic items that transfer this movement from the thinker to the ship.

[The swimming speed of the creature and the speed of the ship this creature guides are equal to 15 × its Intelligence modifier feet. If its Intelligence modifier is 0 or negative, it instead has a speed of 10 feet. Creatures who have the physical swim speed may use it to swim in the Seventh Sea instead, propelling themselves by pushing against water, though this method of movement is frequently more exhausting.]

There’s another way to guide the ship through the Silver Sea. The sea responds to the power of hope [represented by Charisma] with powerful, yet harmless psychic winds that can propel a ship without any need for special equipment. However, many planars are way too jaded for relying on hope. Celestial eladrin are a notable exception.

[Using Charisma to propel a ship works in much the same way Intelligence does, but it doesn’t require special equipment. Another person on board can add 10 feet to the ship’s speed. No more than three people can assist in guiding the ship at the same time. You can’t use Charisma to swim without a ship.]

[DMs should make sure that their PC actually have a real hope in that the winds of the Sea will guide them to wherever they need to go, and are not just going on a cruise for fun or a pile of jink. Remember that neither Intelligence nor Charisma will be of any help once the ship leaves the Seventh Sea. It must be propelled by physical means now.]

Hazards

While the memories of the Seventh Sea are so fragmented that nothing short of divine intervention can restore them, something still remains. The most basic memories congregate in the Sea, giving birth to potential hazards, such as:

Flows of Drive: All determination that infuses minds, even a simple will to stand up from bed or swallow a meal, joins in a web of chaotic currents that criss-cross the Seventh Sea. The largest of those streams can easily throw a ship (or a swimming creature) off its course. Quick-minded bloods actually use flows of drive to reach their destination a bit faster—though a lot of knowledge is needed to determine where the drive flows. [The pilot must succeed on a DC 18 check, using the ability score modifier they are using to guide/swim]

Reefs of Pain: Memories of pain and suffering congeal to become horrible blades that slice body, ship and mind alike. Moreover, they are solid, inhibiting movement of ships. Huge expanses of reefs can create significant barriers, or provide lairs for astral creatures. [Depending on the speed of a ship that rams into them, Reefs of Pain can deal up to 10d8 damage.]

Winds of Hunger: Every creature has experienced hunger and thirst. Winds of Hunger impart those coalesced sensations on every sod who passes through. Creatures who are affected by Winds of Hunger are wracked with hunger and thirst. It doesn’t kill them but it does hamper them physically and mentally [nor does it give levels of exhaustion, but they have disadvantage on all d20 tests]. To offset this effect the creature just needs to eat and drink something real—the “water” of the Sea itself doesn’t suffice—as it would on any other plane. Unfortunately many inexperienced travellers forget to bring enough food, since on the Astral nobody needs to eat or drink. Creatures like fiends who don’t eat are particularly susceptible to this way of thinking. But alas, even creatures who don’t need to eat and drink still feel this consuming hunger. Creatures, who can’t eat or drink by design, such as constructs and some undead are immune to Winds of Hunger. Gnolls and other spawn of Yeenoghu are immune as well, but for another reason — they are so accustomed to hunger that they are just as effective when feeling it. Moreover, they actually prefer riding on the Winds of Hunger.

Island Demiplanes: Demipowers or mages occasionally create small islands—or maybe some of them are drawn into the Sea in a powerful cataclysmic event. Often, these islands can contain beacons and/or portals to other planes (mostly planes with no seas like Ysgard or Mechanus) or Sigil. There are persistent rumors of hidden Astral pirate islands with buried treasures.

Dead Gods: They aren’t as common here as in other parts of the Astral, but occasionally the bodies of dead powers can be found floating in the Seventh Sea. One of the known divine cadavers is Enki from the Sumerian pantheon. His husk has attracted one of the few remaining coteries of Signers. Chant goes they are seeking to revive him.

There are other strange phenomena that can be encountered in the Seventh Sea, such as Slog of Pleasure or the Grasping Sargassus, but for now that’s enough.

Boundaries and Powers

The Seventh Sea is a planar pathway, much like Styx, Yggdrasil, the Infinite Staircase and Mount Olympus. Unlike some other pathways it isn’t tied to one side of the alignment spectrum—in fact, for many years it was been thought that the Seventh Sea connected to six major seas that exemplified non-neutral alignments—the Silver Sea (LG), Thalasia (NG), Aquallor (CG), Stygia (LE), Porphatys (NE) and the Abyss (CE). While other connecting waterways have since been discovered, the name stuck.

How to Get Here: And here we’ve got problems already. You see, the Astral Plane wasn’t supposed to be accessible by anyone save for Powers. There’s nothing like branches of Yggdrasil here. However, its possible to reach the Seventh Sea from any sea in the Multiverse [well—excluding Ethereal and Inner Planes]. You’ve just got be truly lost. What does that actually mean? Who knows! Sometimes sailors find themselves in the Seventh Sea after many months of sailing uncharted waters, but more often than not they don’t. Celestial eladrin and certain renegade githyanki seem to know the dark of this transportation, but the former struggle to give an explanation beyond “planar boundaries are just a metasocial construct, if you understand the Unity-of-Rings” and the latter aren’t willing to chat. Modrons, try as they might, have been unable to discover any laws governing the Seventh Sea—that’s apparently why they send out clockwork ships to roam the Hintersee during each of their processions. But none of those ships has ever been known to reach its destination.

Other races employ much more traditional methods—gates and portals, direct access from Astral and planeshifting spells. Many Powers of the sea have special gates that act as shortcuts to the Seventh Sea.

How to Get Out: This one is straightforward, you just look for a Threshold Wave. The Seventh Sea has plenty of small waves, but these ones—oh, they’re unmistakable. Imagine a tidal wave, higher than any tsunami (and many buildings) of the Prime. Now hide everything and everyone from the deck and ram right into it. Yes, to travel to another plane your boat has to dive right into the wave. The “water” of the threshold wave is less dense than regular waters and won’t capsize the ship, but it can still rip away smaller unprotected items, or creatures.

After the ship—or creature—passes through the wave, it enters a Buffer Sea, a strange region that doesn’t truly conform to the rules of either the Astral (it’s a fully physical place) or the desired plane (for example, the buffer sea of Stygia isn’t fully covered in ice). Hunger, thirst and age accumulated during travelling Astral start to catch up with sailors right around here. While you are in a buffer sea, you still have the chance to turn around and dive back into the threshold wave once again, but once the wave fades from view, you have finally fully left the Seventh Sea. Threshold Waves leading to different planes (and places) have different features — colors, foam, intensity, even sounds matter for the most knowledgeable bloods.

Travel Times: The length of a jorney on the Seventh Sea depends on how familiar the pilot is with their desired destination:

• 6 × 1d8 hours to travel to a threshold wave you’ve passed through before
• 10 × 1d8 hours to travel to an island or to another location (e.g. dead god) that you’ve been on before
• 10 × 1d8 hours to travel to a threshold wave you’ve seen, but didn’t pass through
• 20 × 1d8 hours to travel to a threshold wave or to another location you know of, but never seen in person (travel time may be reduced if the place is described in extensive detail, but it cannot be lower than 20 hours)
• 50 × 1d8 hours to stumble onto a place you never knew about before

Plane by plane

The Silver Sea (Mount Celestia / Lunia) — Threshold wave: Quiet wave of deep blue water that feels like it is made of night sky. The buffer sea is dark and has the properties of holy water. However, Mount Celestia can’t be seen yet. It is possible (if unlikely) that other layers of Celestia also have large bodies of water, but ways to them have not been found. The ever-vigilant archons keep close watch for any possible intrusion from the Seventh Sea. This is a demanding task, considering that the Seventh Sea can drop a sailor in any place far enough from land, but the archonic net of beacons of faith and watchtowers is sufficient to protect the Threshold of Lunia itself. And of course, archons have plenty of gates to use the Seventh Sea in pursuit of their own goals.

Thalasia (Elysium) — Threshold wave: A clear and bright wave that sparkles with light. Buffer sea is indistinguishable from Thalasia itself. This route is very popular among good-aligned Astral sailors, as Thalasia is generally quiet and very pleasant. Evil bashers should beware not only the guardinals and other heroes (who are in abundance here), but also the evil-resisting properties of the plane itself. Some say that it’s much harder for bloods with bad intents to find a threshold wave to Thalasia.

The Whalegrounds (Beastlands) — The Beastlands are a weird place, even as far as the Outer Planes go. This sea is very far away from explored parts of Beastlands—in fact it is so far that Selera and Noctos are said to float right above it. Its said that the Whalegrounds are somehow in all three layers at ones—swimming towards Selera brings you to Krigala, towards Noctos — to Karasuthra. Thinking about it for too long makes my brain-box hurt, so I’ll just talk about how to get here: the threshold wave is a mighty tsunami, that often has wayward fish caught in it.

Aquallor (Arborea) — Threshold wave: A powerful, gigantic wave that foams in rage as if it was sent by the powers themselves. The buffer sea is typically calmer, but otherwise indistinguishable. Aquallor or Ossa is a dangerous place to set sail — it is fickle and often stormy. Moreover, there are fewer gates to the Seventh Sea than, say, on Celestia. Try to search for the realm of the Sea Tsar — bloods there not only have gates, but build impressive flying ships to travel both by sea and by air.

Donbettyr’s Domain (Ysgard / Ysgard) — While Ysgard has its fair share of bodies of water, most of them aren’t big enough to connect to the Seventh Sea. Earthbergs generally aren’t wide enough to support great seas. But Donbettyr, the power of seas and rivers from Ossetian pantheon, couldn’t be stopped by such limitations. He’s tugged together several earthbergs to create a stormy sea that holds his magnificent palace. This sea is just big enough to allow threshold waves to form—and form they do. These waves are huge and unlike others can actually capsize smaller ships. Other sea-related powers like Aegir keep gates to the Seventh Sea in their domains.

Limbo — Sometimes the ever-churning chaos of Limbo randomly forms temporary seas. Threshold Waves to such seas don’t look like regular waves, but like floating heaps of weird junk from stones to cakes (they still are the same weird portals, and cakes are a lie). There’s no buffer sea, the wave just dumps you into the bubble of air and water (at least you best hope is that it’s air and water). These bubbles return to the primordial chaos that birthed them very fast—often fast enough to trap the ship in a chaos-stuff of Limbo.

Ruinous Sea (Pandemonium / Pandesmos) — Not many people knew of these sea of chaos and swirling colors before a great battle between forces of Lolth and Miska the Wolf-Spider took place here not too long ago. Threshold waves to this blasted place fill the Silver Void with their cacophony. They glow with sicky light and have lightning running throughout the streams. Once you leave the buffer sea, torturous winds of Pandemonium pick up the ship—most often with disastrous results. Fortunately, there aren’t many waves leading to the Ruinous Sea. Unfortunately, no one has bother to chart the gates to leave it.

Abyssal Seas — there are way more layers of Abyss than it should be, and there are way more seas on these layers than it’s convenient to list. But the Seventh Sea most typically opens into the 50th layer called Ishiar, the Ocean of Despair. It is an ocean of stagnating stinking water, which is relatively peaceful, if you don’t count myriads of demons, half-fiends and the demon lord Dagon. Some say this region used to be the buffer sea of Abyss, until Dagon took and “widened” it. Perhaps that seems unlikely, but well, you can expect anything from the Plane like this. Not to mention that the “current” buffer sea is barely any different from the realm itself. From the Ocean of Despair (or, more rarely, directly from the Seventh Sea) it is possible to reach many more Abyssal Seas like those in the domains of Demogorgon, Yeenoghu, the Queen of Chaos and Troyan, layers like the Ice Floes and the Burningwater and many, many more horrors. The threshold wave to Abyss can have different colors, but almost always oozes with disgust and hatred.

Porphatys (Carceri) — Threshold wave: slightly greenish, foaming wave of water, that burns everyone that comes through it. It doesn’t do damage, but feels like acid — Carceri greets its visitors with pain. The buffer sea is notable for absence of acidic snow. However, sometimes the buffer sea is just absent, and the threshold wave disappears instantly, essentially being a one-way portal. How to return to the Seventh Sea from Porphatys is pretty much dark—even if any of its prisoners had a way to make a gate, this gate probably wouldn’t last, not with their attitude (although perhaps that one orc goddess could give you a pass). So when you’re being duamped onto a far-flung Carcerian orb by a wayward wave, your best chance is to abandon the ship—or to try and become even more lost.

Sea of Waste (Gray Waste / Niflheim) — Nobody has bothered to give this sea a name. It’s simply “the sea where Arawn lives” or “the puddle Hel’s warriors set sail in”. Threshold wave: Calm and gray. Once a body leaves the buffer sea, Gray Waste color draining and Niflheim’s mists start to take hold. There really is nothing there. Aside from some sea serpents, but like, who cares. Try and find the gate at Arawn’s place.

Stygia (Baator) — Threshold wave: A maliciously dark wall of water, sometimes with chunks of ice on top of it. As you leave the buffer sea, you’re completely surrounded by ice floes. Baatezu closely observe any and all possible incursions from the Seventh Sea. They do have a couple of gates, but you may need to garnish a lot of nobles to access them

End of the Styx (Acheron / Ocanthus) — This is a rarely found-one. It seems that the “bottom” of Acheron, an infinite sheet of black ice has a tendency to partially thaw. It does so regularly, in accordance to some unknown rhythm of Acheron. When it does, a shallow black ocean forms. It is believed that this place is the final destination of the River Styx, however the black ocean water doesn’t have its memory-draining properties (it’s just poisonous from all those heavy metals in it). What it does have is a bismuthine palace of Charon and his merrenoloths. It’;’s not a great place to visit, that’s for sure. To be entirely fair, visiting this entire sea is even more of a death sentence than usual: once the ship leaves the buffer sea, it is torn apart by Ocanthus’ vorpal shards, unless protected by powerful magic. Threshold wave: Black, oily and weirdly orderly.

Square Sea (Arcadia / Abellio) — This sea with unnervingly straight shores is a shared creation of some Vietnamese and Khmer powers. It has almost no waves and its coast is littered with docks and fortresses. Threshold waves are also weirdly geometric in appearance and glow with metallic light. Ships of einheriar and Arcadian avengers constantly patrol the Square Sea for any would-be invaders.

There are no known instances of threshold waves leading to Mechanus, Bytopia or Gehenna.

Hintersee (Outlands) — Threshold wave: A plain old regular wave. Even too regular. Hintersee is the cold and windy sea that touches the gate-town of Glorium. It is the home of the Inuit pantheon, but isn’t all-too notable otherwise.

Prime Material Seas — Threshold wave: Seems regular, although somehow more real than the rest of Astral. You can feel the salty wind and cries of seagulls coming from the wave. There are billions of seas on the Prime Material Plane — some are pleasant and some are more horrifying than most Abyssal layers. One of the more notable examples is the world named Olefin that has drowned long ago due to the ritual gone awry. Feywild and Shadowfell, being reflections of the Prime, are also accessible in this way.

Elemental Plane of Water — the Seventh Sea is a part of Astral and thus cannot be naturally connected to any of the Inner Planes. However, many powers dwelling there do make gates between their domains and the Seventh Sea.

Sigil — in a same vein, temporary portals sometimes open between the Seventh Sea and Ditch. Not many bloods’ve been able to capitalise on it.

Other Weird Places — If you listen to bubbers and sailors, you’ll can hear all sorts of ridiculous tales. One of those frankly untrustworthy sources told me how he’d sailed the magenta-colored sea with a continental-sized fiend bathing in it, another about an ocean of milk and honey. Most of those tales describe nothing more than a drunk hallucination (or a layer in the Abyss — there aren’t too many differences). So-called Cordant Planes are on everyone’s bone-boxes right now, so of course berks are now talking about sailing to K’un-Lun, Avalon or Discordia.

Astral — That one’s easy. To reach the Astral proper, you simply fly up. Once the Seventh Sea fades from view, its gravity stops affecting you. To reach the Seventh Sea from Astral you must fly and concentrate on it as per regular Astral travel rules.

To determine whatever plane the randomly encountered threshold wave leads to, the GM can roll a d100:

• 01-10 — Lunia
• 11-20 — Thalasia
• 21-30 — Aquallor
• 31-40 — The Ocean of Despair
• 41-50 — Porphatys
• 51-60 — Stygia
• 61-65 — Prime
• 66-70 — Sea of Waste
• 71-75 — Square Sea
• 76-80 — Whalegrounds
• 81-86 — Hintersee
• 87-91 — Donbettyr’s Domain
• 91-93 — Ruinous Sea
• 94-96 — Some different layer of the Abyss
• 97 — Limbo
• 98 — End of the Styx (roll again, if End of the Styx doesn’t exist in this time of year)
• 99 — An unknown sea on a known plane (includes Cordant Planes as part of Outlands)
• 100 — An unknown plane

For a gate, replace Porphatys with Elemental Water and Ruinous Sea with Sigil. The Ocean of Despair is replaced by “any appropriate Abyssal layer” and Donbettyr’s Domain by “any appropriate place in Ysgard”.

Inhabitants and sailors

Astral Fauna — Most astral creatures avoid the Seventh Sea, but astral whales and astral streakers do visit this place. They seem to be unaffected by its gravitational pull. Astral dreadnoughts have been observed to drink the water of the Sea.

Astral Gazers — The only true natives of the Seventh Sea look like horrible eyeless serpentine ichthyosaurus. Instead, their single giant eye can be found in their mouth, where their throat should be. When the astral gazer opens its maw, its gaze turns creatures it focuses on into the spectral water of the Sea. Should this attack not be effective, the horrible aberration uses its teeth instead. Astral gazers do not live in other parts of Astral and they fortunately cannot exist on any other plane. Like astral dreadnoughts, they stalk the Seventh Sea in search intruders and attack smaller vessels and swimmers. Astral gazers are known for organising their strikes when it comes to dispatching of bigger ships.

Lost Ships — Once in a while, a ship with its crew from Prime gets “truly lost” and winds up in the Seventh Sea. Some of such crews figure out a way to escape to other planes (with mostly detrimental results). But others lose their hopes so completely that their boat stops moving at all, and they become even loster than lost. Since sailors cannot die from hunger or age, they can exist in half-dead state for many centuries. However, most of these hopeless sods eventually get scragged by fiends, or eaten by astral gazers.

Githyanki — The gith can travel the Seventh Sea just as well as other parts of Astral using their Astral ships. A renegade clan of githyanki predominantly inhabits the Seventh Sea and hides from thralls of Vlaakith (or so they claim—some suspect that they aren’t in fact being searched for). They earn their living by whaling — something that earned them undying hatred from archons and eladrin alike.

Archons — Archons vigilantly protect borders of Mount Celestia, and they are very interested in the Seventh Sea and its connective qualities. Some of these bloods are actually living ships themselves — submarine, brig and galleon archons are special casts of archons devoted to sailing all manners of seas. And what ship can steer itself better than a sentient one?

Guardinals — The guardinals are similarly interested in the Seventh Sea. At least two of their types seem to be tailor-made for exploring it: marlin-headed makairals and albatross-like diomedals. Guardinals do not build warships themselves, but they use those built by denizens of Thalasia.

Eladrin (I refer to my own version of eladrin, detailed here) — well of course they would want to explore the Seventh Sea. Well of course they have an Aestetica for that purpose. It’s called mairne, and eladrin who adhere to this Aestetica are great captains and adept sailors, who love the feeling of freedom oceans bring. While these eladrin can access the Seventh Sea from anywhere, they still prefer using gates, especially those in the City of Sun and Rain. In fact, these city is a gathering place for all celestial naval escapades. Golden Galleon, the famous masterpiece of a ship belonging to Faerinaal, has visited the Seventh Sea on multiple occasions. Novieres too visit the Seventh Sea often, though they prefer accompanying ships.

Slaadi — Slaadi can swim, so they use the Seventh Sea on occasion. Not often though.

Chaos Kraken — Speaking of chaos, these monsters originate in Pandemonium and seem to be able to shift into the Sea too. They are somehow even more violent than regular kraken and pose great threat. In other ways they are identical to kraken, but have the immunity to damage from chaos-stuff—be it from Limbo, the Ruinous Sea or certain levels of Abyss.

Demons — Tanar’ri surprisingly rarely employ the Sea. It isn’t much of use in the Blood War, considering how protected Stygia is. But of course, demons wouldn’t miss a chance to use this planar pathway to harass denizens of the Upper Planes. Tanar’ri prince Yeenoghu frequents the Seventh Sea with his pet monster Crokek’toeck, and wastriliths are common here.

Yugoloths — Using the Seventh Sea is a bit inconvenient for these fiends, as Gehenna doesn’t have seas (nor do the most accessible layers of Gray Waste and Carceri). Of course, they still try to control it, and merrenoloths and hydroloths are frequently hired by fiendish sailors, but they’re are not nearly as common there as on Styx.

Devils — While tanar’ri aren’t keen on using the Seventh Sea in their attacks, baatezu exploit it as they might. Or at least Levistus does—he has built a number of very impressive shipyards that churn out various ships from relatively small cruisers to city-sized icebreakers. Most awe-inspiring of these warships are still stationed in Stygia for some unclear reason. Perhaps, they simply wait for the right time. Or maybe, baatezu of Stygia have realised that the ship that is too big is not actually viable in combat, but can’t risk admitting this to their superiors.

Modrons — While modrons do have clockwork ships, they are rare guests in the Seventh Sea, mostly because Mechanus doesn’t have seas to speak of. They are somewhat interested in it, however, and send their longships to roam the Hintersee during each Modron March.

Powers and their Servants — No powers live in the Seventh Sea, however many of them use it to their advantage. Bloods like Poseidon, Aegir, the Asathalfinare and many other powers have made efforts to create the portals to and from the Seventh Sea and destroy portals of their opponents through the hands of their followers. However, for some reason the Seventh Sea remains unconquered. Perhaps, it is meant to represent the ultimate freedom of movement that bows to no deity.

Planars — Recently mortal planewalkers and traders have invented a multitude of vehicles to travel the Seventh Sea. It is quite important for trade, since, even accounting for Sea’s unpredictable nature, it can be one of the more convenient planar pathways. Even the Via Romana doesn’t allow for such large quantities of goods to be transported from one place to another. A canny sellsword and spellslinger can make plenty of jink offering their escorting services.

Encounters and Plot Hooks

• A ship from Portico (Thalasian burg) is wrecked by Reefs of Pain. A pair of diomedals approaches your vehicle and asks for help in saving passengers.
• Your way is barred by grasping sargassus—a magical kelp, that clings to any astral ship and incapacitates its pilot. You see a chaos kraken approaching you…
• A heavily damaged galleon archon seeks escape from a baatezu destroyer with its escort.
• You encounter a modron longship. Modrons will usually to return to Mechanus, but these bashers all are out-of-ordinary and seem to have gone rogue.
• You stumble upon a threshold wave to Poryphatus, that moves towards you unusually fast. A successful Perception check reveals a demodand that seems to be guiding it.
• Your ship is picked up by Winds of Hunger. As you are wrecked with hunger and thirst, you see a band of gnolls riding on kerriliths (giant chiasmodons). The stomachs of the kerriliths seem to be full with something.
• An eccentric young captain on an Astral yacht with crimson sails searches for a hidden island in the Seventh Sea, and claims to be looking for his long lost love. However, if PCs decide to stick around, they realise he isn’t hoping for a sweet reunion.
• You encounter a half-broken lost ship with a ghostly-looking crew. They ask for help in returning to their Prime world — Athas.

Further Reading

• Ships of the Seventh Sea

Source: Return to Crab [see here], based on an idea by Jon Winter-Holt. Canonwatch: This planar pathway and its features are non-canonical homebrew.