Your party now sails the seas, whether as hired crew or captaining their own ship, and encounters await them!
Maybe you’re preparing to use our Ocean Encounters d20 Chart, after inspiration to run Ghosts of Saltmarsh, or crafting your own campaign. To help you along, here are some expanded explanations for the encounters featured in our chart. Under each of them, you will find a more detailed description of the encounter’s context, followed by tips and advice. This should give you all the ideas and guidance you need to make the encounters your own and run them in your game.
We also have a second part, containing details for encounters 11-20, which you can find here.
1 – An abandoned, yet undamaged ship floats in the water. Aboard is a single man, scrawling strange runes across the deck.
A single ship floats, bobbing slightly against the waves, it’s sails raised and anchor lowered. As the party’s vessel approaches, they can hear no crew aboard, and no lights are visible below deck. Filled with curiosity, they bring their own ship to a stop and move to board. They make their way over and are met by the surprised gaze of a single remaining crewman. In his hand is a knife, which he has used to carve a dozen concentric rings of symbols and text into the wood of the deck. He stares at his visitors, scrambling to form an explanation for his predicament.
Like many ocean encounters, this gives a great level of freedom for deciding the context of the stranger. For a start, who is he? Deciding if he is the ship’s captain, or simply a crewman, is a good base. Similarly, what business was the ship involved in? From this, who could their enemies be, and who could be capable of the scene in question? The single character for the party to interact with gives an easy jumping-off point for creating the encounter and limits the need to juggle voices and character knowledge. Having them only meet one character also helps him to be memorable, which can turn a one-off encounter into a story told for years to come.
This particular setup suggests magic, and ocean encounters can be a great way to involve the water plane. For example, maybe the crew had appealed to a creature of another realm but were lost in their attempt. Now the sole survivor is trying to make a similar deal for the lives of his crew. If the party is high enough level, have another rift open and let them fight/bargain to reclaim the lost sailors. Or perhaps an ancient voice had spoken from the deep, compelling the crew overboard, and this last man scrawled runes to protect himself. But now the voice returns, and the party is unprotected. If the characters are especially low level, light on resources, or you’re just after a shorter, even comical encounter, maybe the man really is just insane.
If you’d like an example of a backstory for the man, have a look at the story attached to our Ocean Water Tiles!
2 – A thick fog and storm drifts over the ship, and the shadow of a much larger vessel lurks within.
As the party sails through open waters, they approach a mighty wall of fog and thick clouds. It moves to swallow their ship as if seeking it out. Minutes later, the party’s ship is enveloped in the fog, unsure of what to do other than continue on their heading and hope to breach the other side. But it doesn’t take long before the silhouette of an enormous ship appears near them. Growing closer and darker, the shadow pulls up alongside the party’s boat, and figures on the opposite deck prepare to board.
One of the best avenues to crafting ocean encounters is to make use of tension. With the terrain being a wide open plain, the possibility of escape is significantly lowered, forcing players to confront the chosen threat. This particular scenario plays further into this, by making the enemy appear to be in some form of control over the playing field.
Due to the hostile nature of this encounter, it lends itself best to a boss fight of sorts. The party is outmatched, so they may attempt to run. But if you expect your party to prefer combat, emphasize that it needs to be played strategically. For instance, the use of fog means that the opposing ship has at least one powerful mage. However, the rest of the crew and their actions should be finely balanced to account for party level. If they are lower, perhaps they will leave once the party proves itself a nuisance to them. If your characters are more advanced, you have more freedom to lean into the magical side of the encounter. Have the mage involved in the fight, or even change the faction from being pirates to something more magical or sinister. Perhaps Genasi units?
But you could also use this to kick off an entire campaign or campaign chapter. If you wish to expand the encounter further, maybe this first ship is one of many, led by an infamous pirate king? By making the first brush with a new faction memorable, you further motivate players to learn more about them. If one ship and crew is this powerful, what kind of man would they call king?
3 – Illegal animal traffickers had been ferrying exotic beasts, but were slaughtered when some of their trophies broke free.
The first sight of the forgotten vessel was the torn sails. The party could see the long claw marks from a distance, and closer inspection reveals similar damage on deck, amidst pools of blood and rended corpses. Even the outer hull has ominous marks, and a movement can be heard in the shadows. On the lowest deck, hidden in boxes of cargo and supplies, is a set of cages. The bars have been bent and broken, and whatever beasts escaped are still on the loose.
It may sound obvious, but an interesting way to approach ocean encounters is to simply take monsters that would normally apply to a land-locked encounter and throw them into a different context. The choice of creature will depend on level as always, but almost all beasts and monstrosities will become more dangerous when trapped. A basilisk is a threat in the open, but even more so in the constricting lower decks of a ship. A multitude of different enemies should be used and can be taken from any and all climates, as it only helps to illustrate the nature of the ship and its crew.
For this encounter, try to build a story behind it. Have the party discover more bodies and tracks as they explore lower in the decks. Build tension, and slowly make what happened clearer to the players. This will stop the encounter from feeling random. Even better, it can open up options for further story beats if the party decides they want to track down the people who would buy the beasts. If you want to lean even more into the narrative, have the party find one or more survivors of the slaughter. Whether they are repentant or furious, or on the brink of death, it gives the players more choice.
Similarly, don’t neglect to build a story in the location itself. Evidence such as documents and ledgers should be present on board for them to find and piece together what happened. Arrange the bodies they find in ways to show how they died and indicate what killed them. Some of the crew might have been killed from the shadows, but others would have fought back. If your players tend to ignore these kinds of clues, do not be afraid to give a survivor more information.
4 – The party’s ship is slowed to a halt by tendrils of constricting seaweed. Within the underwater forest hides a sahuagin ambush.
As the party travels along in the sunny light of day, they notice their ship gradually decelerating. This progresses until the last of their speed is suddenly drained, leaving the ship motionless. A quick investigation reveals that the bottom of the hull has become entangled in thick, dense strands of seaweed that reach up from the darkness of the deep. Unknown to them is the ambush of sahuagin hunters that lie camouflaged in the plants, waiting for whomever is sent down to cut the vessel free.
Ambushes are a staple encounter format, so the key here is to disguise it. By presenting the conflict as a natural occurrence until the ambush is sprung, you force your players to think on their feet and quickly adjust their plan. If they first send non-player crew members down, have the first of them not come back up, provided the character is nonessential. If the character is required in some way, dial it back to an injury. This should put the players on edge, which will then have them plan how they want to deal with an unknown enemy. Once a player character does venture down, give them the opportunity to recognize the ambush before the sahuagin strike. It could be as simple as a blur of movement, but it gives them a chance to react before being hit by damage.
A lot of the time ocean encounters are used as a way to give the players something to do while traveling. This particular example allows you to inject some relatively quick combat in without crafting a story or worrying about plot deviation. Your players will be happy for you keeping the pace moving, as well as having a simple combat encounter to stretch their legs. It is also free of any moral quandaries, as the players are acting defensively. And we all know that sometimes you just want to hit something and not worry about who’s the good guy.
It is important to remain careful with how the sahuagin act, as drowning can quickly snowball a character’s health. One solution to these issues is always to have the enemy be careful of their own losses. After all, an ambush squad is unlikely to sacrifice themselves for a single boat.
5 – The party happens upon what they think is a crewless ship. They don’t realize that the previous crew fled from a nest of mimic stowaways.
The sun is setting as the party finds themselves passing a ship. The lifeboats are missing and no movement can be detected, yet lights flicker within. If they venture inside, they find a well-furnished captain’s quarters and crew chambers, but no crew. It’s easy to see that they fled the ship, as the food stores have been emptied. What they cannot immediately see is the rows of teeth awaiting inside the remaining barrels and furniture.
The use of mimics is a personal favorite and a beloved part of the game. Mimics can present a real danger, but it’s often best to use them to inject some levity into an environment that becomes hostile very quickly. One of the most enjoyable encounters I have run was a mansion filled with mimics, animated armor, and rugs of smothering. It gives a tense environment that forces players to think about their movements in detail. Everyone also gets a laugh when the party bard kicks a barrel out of his way or tries to drink some wine. They rarely expect to find the objects sticking to them and sprouting teeth.
Similar to the escaped animals scenario, the key here is to spring the trap once they’re deep enough in the boat. Ocean encounters, especially abandoned ships, rely on the party not being able to immediately leave. One way to do this while keeping it interesting is to have mimics moving when out of sight. This is how I put my players on edge in my mansion encounter. By having the sounds of movement in other rooms, and furniture changing positions out of sight, the players will slowly form their own assumptions. My players were sure it was ghosts.
Do note that you need to be prepared and specific in describing object locations, and know which are mundane and which are alive. It’s paramount that you keep it fair for players. This goes doubly so when you’re having them be specific about what they do and don’t touch. But only start asking for specificity when they know what is happening. You don’t want to ruin the surprise. Once they make it deep below deck and have interacted with other furniture safely, spring your trap. Then sit back and watch them try to escape while fearing every chair and candle.
6 – A rocky shoreline holds a ship’s broken ruins, with illusions of crew waving for help.
The party’s journey has them following an island’s coastal cliffs. They keep their distance to avoid being swept onto the jagged rocks that litter the waters. The evidence of less cautious voyages is warning enough. One such ship has been split in half against a stone shelf and loudly groans with each passing wave. The party can see survivors on the deck, frantically waving for help. But these crewmen are only illusions, cast by predators waiting just out of view.
Boat travel will often be along a coastline rather than in open waters, so it’s useful to have some ocean encounters that depend less on the ‘ocean’ part. These locations often come with terrain hazards for straying too close to land. Avoiding this is often easy, but what happens when an encounter forces players to deal with the hazard instead of avoiding it? Like most encounters on this list, the broken ship presents multiple layers of danger. First is simply navigating the rocks in their choice of boat, but then comes the ambush.
Avoiding the rocks should not be too difficult for discerning players. Assuming they take a small lifeboat, a simple skill check for whoever is rowing should suffice. If you want to up the ante, you can make rolls to determine the strength of waves as they hit. Just be careful to keep it fair, as this is only step one of the encounter. They still have to fight, and then row back in a likely weaker state.
Pirates might seem like a straightforward choice of opponent, but they do present questions that the players might have. If they are seafarers themselves, where is their ship? Do they have a base nearby? Is their goal to steal the player’s ship? Why use illusions? It can most certainly work but does require extra background thought. If the encounter is to be more ‘one-and-done’, the illusions could be being cast by magical sirens. Or maybe they are locals to the area, preying on sailors for gold or, more sinisterly, food. Not every encounter needs to have a story behind it, and using creatures with more straightforward motivations keeps the story from being more than it needs to be.
7 – A strange, ghostly ship comes into view, with spectral apparitions on board. Below the surface, a creature waits for its lure to attract prey.
As the sun sets and the last light of day dances along the ocean’s surface, a ship seems to form out of creeping shadows. Ghostly and glowing an ethereal blue, the vessel is manned by the specters of a long-dead crew. They do not appear hostile, instead beckoning the players toward them in an attempt to communicate. Somewhere below the surface, an enormous beast casts the light of its bait, waiting for a curious ship to stray close enough.
Let’s be honest, when most people think of ‘ocean encounter’ one of their first three ideas is ‘ghost ship’. It’s a classic, and for good reason. But it’s for that reason that the ship itself is not the true encounter here. It also presents a challenge as a Dungeon Master, because your players will know to be cautious. It may be very difficult to have your players choose to approach the ship instead of avoiding it, especially depending on the characters present. The key factor is to not make the ship appear at all hostile. No pirate flags, no cannons, no armed crew. Rather, have them appealing to the party in some way. They could be calling for help, celebrating and offering a drink, or even attempting to warn the party of another, fake, danger.
Once your party is successfully lured, the next step is deciding exactly what lies below the surface. While krakens and hydras are fantastic ideas for a fight, they will quickly destroy a low-level party. A better approach would be homebrewing a creature. Look at sea monsters in popular fiction, and adapt their themes. A fun idea is to have multiple tentacles breach the surface, attacking crew from off the ship. Damaging the tentacles can slowly wear down the creature as a whole. Only showing part of the beast keeps players and characters guessing at what it truly is. If you’re still struggling or short on prep time, replace the single larger beast with a sahuagin attack.
8 – The tip of a ruined tower peeks out from the ocean’s surface, in a place where all maps say should be empty.
While sailing through the open ocean, the party sees something rising out of the water. They identify it as the highest point of a dilapidated tower, still holding itself together against the waves. They check their maps and history books and find nothing to indicate that this area is populated or ever was. Looking down, the tower extends into the dark of the waters. What secrets could lie in and around this steadfast monolith?
A few suitable tower battle maps…
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Unlike many of the other encounters here, this one is entirely open-ended. This means you can have it be peaceful or involve combat, woven into the story or entirely separate. It will all depend on the campaign. The most contained option is to have it be exactly what it seems: a ruined tower, and nothing more. Your players may simply ignore it, but if they explore there should be some reward. A chest could have been left behind by the old resident, magically sealed to preserve its contents. Removing the chest or damaging the tower could cause a collapse, forcing an evacuation to avoid drowning. In this case, the rewards should reflect the context, so any gold could be accompanied by a scroll of water breathing or control water.
Alternatively, this encounter could be expanded almost limitlessly. The tower could be rising from the debris of a great city, lost to the currents. To continue on this, maybe predators now lurk the streets or sahuagin are actively looting. The more capable characters are at surviving underwater, the more you can include. Otherwise, it can be as simple as having them make skill checks while diving for relics. Perhaps the building’s broken state is a guise, hiding the laboratory of a hermit wizard in its lower levels. Maybe he is home, and pleasantly confused at receiving visitors. And maybe the wizard’s experimental studies grow darker and more sinister as they venture lower in the tower.
If you are looking to expand on the encounter or the wizard, think about combining it with other encounters. The tower could be protected by the effects in Encounter 10, or the hermit may be the cause of the mimics of Encounter 5. Think about his motivations and how he interacts with the world around him. Is he allied with sahuagin, letting them hunt or even assisting them in exchange for sanctuary? Perhaps they fear him, and the seas surrounding the tower are eerily quiet. More importantly, why is he there? He may be studying something nearby, or took the tower for its seclusion. If it was always his, what cataclysms befell it to have it now stranded in the ocean?
9 – A school of large, brightly colored fish swim alongside the boat. They could feed the crew for days, but their meat is highly hallucinogenic.
Night has fallen, and only a small number of the crew remain on deck while others rest. The seas are calm and kind, but through the darkness, a soft glow illuminates the side of the ship. Looking over, the characters and their crew see a school of fish, each as large as a dolphin, swimming alongside them. The fish give off bioluminescence that shifts colors. They would be an easy source of food, feeding the crew for multiple days if they were to be caught. But the characters are unaware of their hallucinogenic side effects, something a few crew members are aiming to have fun with.
Not all ocean encounters need to be combat-focused. One of the best ways to break up the pace of travel and keep your players engaged is to separate combat encounters with moments of humor and levity. This particular instance could, of course, lead to nothing if your party simply ignores the fish. A way around this is to have several members of the crew know the effect of the fish, and attempt to motivate the party to catch them. The focus is still light-hearted fun, so don’t have them be aggressively argumentative or even good at lying. If the party can coax the truth out, or are able to identify the sea life with a knowledge roll, give them the option of whether they want the effects. Many players will, for the sake of hilarity.
It’s important to know exactly what the effects are. The hallucinations can be used a dream sequence-esque moment for revealing character backgrounds, or benign visions of faeries and wisps. Double vision, vertigo, phantom lights, you can do almost anything with it. And perhaps the effects of the fish have not faded by the time the next encounter arrives, or even when the party reaches port. The purpose here is to give your players a reprieve from the tension of many of the other encounters.
10 – A beautiful aurora appears in the night sky and a warm rain falls, but winds blow in all directions and stars seem to move, disrupting navigation.
During the night, the sky is gradually lit up by a shifting aurora. The dancing streams of color are unusual for the area and draw the crew to the deck in awe. It begins to rain not long after. But the rainfall is not coming from any visible clouds and is soon accompanied by winds that seem to shift and change in different directions. Constellations appear to drift behind the aurora, as the winds push the sails to and fro. It’s not long before the beautiful spectacle becomes a nightmare for navigation.
The ocean is both a beautiful and dangerous place, and some of your encounters should reflect this. Unlike the other encounters with background stories and contexts, it’s perfectly okay to run this without a defined cause. It’s a magical world, and sometimes strange things happen without explanation. This is entirely up to you as the DM of course, and the undefined nature of the encounter means it can be repurposed to fit a number of situations. It could be that the players did not make the appropriate offering to an ocean god, or strayed into waters where other realms push on the borders of the material plane. The weather could even be a protection spell, maintained by the same hermit wizard in Encounter 8 as a way of dissuading sailors from finding him.
This encounter also acts as a test of your characters’ skill and players’ thinking. As mentioned, it should be entirely possible for them to maintain their heading with the right actions and checks. This would, of course, come with the reward of not having travel delayed or offset. The satisfaction of making it through an encounter without negative effect can be a great feeling as a player, especially if it then leads to further discovery. If they do fail, the disruption should not put them more than a day off-course. Too much punishment from a short encounter can cheapen the experience, though this does depend on the campaign and those involved.
That concludes our expansion of the first ten encounters in our Ocean Encounters d20 chart. Feel free to leave your opinions or ideas on how else the encounters can be run. If you use them, we’d love to hear how they play out in your games!
Ocean Encounters Part 2 will be coming soon, containing the remaining ten. Until then, happy sailing, and please check out the boatload of maps and assets we offer below.