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  • To Graven Grotto – Deep Ocean Monster Encounter for D&D 5E
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A pirate grotto encounter with a sea hag and her minions from the ocean depths, with stat blocks for D&D 5E.

The mayor of a coastal town has a job for those amenable to danger and discretion. Should a group of adventurers show interest in the task, he invites them into his office, provided that nothing spoken in the room is to ever leave it. And should they accept and accomplish the task he presents, they will, of course, be adequately compensated.

The mayor explains his predicament once the party agrees to his terms. Expected maritime shipments have not been delivered and he worries both for the goods and the men transporting them, whom he has a long-time business relationship with. He wishes for a group to walk the coastline and look for any sign of trouble. Should they discover why the shipments have stopped, they are to do anything they can to rectify the situation before reporting back to the mayor.

If pushed for details about the shipments, his business partners, or the need for secrecy, the mayor elucidates the matter. He explains that his business is an under-the-table dealing with a faction of pirates whom he allows to sail undisturbed in exchange for a small cut of their profits. While no one else in town is aware of this income, the mayor is quick to assure the characters that he puts the money towards the town’s benefit.

Should the party accept the task, the mayor provides them with a map of the nearby area, marked with the ships’ expected path along the coastline. If he revealed the additional information about the pirates, he also marks a hidden meeting point that the pirates use to offload and transfer their cargo and to relax between voyages.

Pirates Grotto - Tropical - Dark - Large preview

The Pirates’ Grotto

Your makeshift path through sharp underbrush continues along the cliffs’ edge, punctuated by the sound of waves lapping at the rocky slopes and the salty smell that is cast up from them. As you carry on, the sight of something in the water catches your attention. A shattered wooden spike pokes from the waves, disappearing and reappearing as the surface rises and falls. Slowly, you begin to spot other fragments, as well as larger shadows that loom motionlessly under the surface.

The water washes through the cave opening into a shadowy grotto, where it splashes against the starboard side of a wrecked but upright ship. The vessel itself is pressed against the inner shoreline within the cave. It is held firmly in place, though there are holes in its hull, its masts are broken and stripped of their sails, and the grotto’s foliage has climbed the outside and onto the deck. Behind the ship glows the flicking light of a fire.

The pirates’ grotto is a secret meeting place that the pirate crews have used as a checkpoint for their operations. The secluded cave allows them to store and transfer goods without fear of their ships being spotted meeting on open waters. As one might expect, such a meeting place developed into a sort of home base for the pirates, who would spend their downtime in the idyllic cave and a small lookout camp above its entrance. They outfitted the wrecked ship with living quarters and a makeshift bar and nicknamed it the ‘Wreck and Rabble’.

Within the last month, the pirates came under attack by a sea hag and her minions. The creatures struck from the depths and caught the pirates with their guard down, overpowering the crew before they could defend themselves. The hag, drawn by her disgust for the beauty of the pirates’ many treasures, has ensured that every coin, jewel, and trinket has been cast to the ocean floor and left to lose its luster. She and her underlings have also kept the grotto’s fires burning, creating the illusion that naught is amiss. Other ships have since approached and likewise come under attack, sinking in the waters outside the cave entrance.

Finding the grotto. The entrance to the grotto is a cave hidden along the cliffs. A character traveling nearby that succeeds on a DC 14 Wisdom (Perception) check notices either the hidden camp above the cave entrance or the broken masts of sunken ships.

The characters can also be given the location of the grotto by the town mayor if they convince him to reveal his deal with the pirates.

Hiding henchman. To uphold the illusion that the grotto is still inhabited and to lure in more pirates, the sea hag has positioned many of the pirates’ bodies around the cave. Some are posed together around campfires and at the bar, while others are propped up by wooden planks and spikes to appear to still be alive. Hiding within the bodies are resting seabed zombies. Other zombies move around the camp, carrying out the sea hag’s orders.

Map & Asset Downloads

The pirates’ secret base is none other than our new ‘Pirate’s Grotto’ battle map, which is ready for you to download and use! We also have the pirate’s cove to act as the grotto’s exterior, as well as a number of other maps and assets that you could include, either in or around the cove or along the party’s journey to find it…

Monsters from the Deep

The grotto is still inhabited by the sea hag and her minions, who continue casting pirate treasure into the ocean depths. She has further bolstered her forces with the risen corpses of the pirates. Many lie in hiding or disguised as dead pirates, waiting to attack anyone that comes near or to be called to the hag’s side.


Seabed Zombie

Seabed Zombie 3 - Monster Token
Seabed Zombie 1 - Monster Token
Seabed Zombie 2 - Monster Token

A groaning undead shambles forward, its green skin dripping with water. Barnacles, seaweed, and other oceanic growth cover both its body and the rusted trident that it drags with it.

Identical in many ways to their more common, terrestrial counterpart, seabed zombies are corporeal undead created from the risen corpses of pirates and sailors. These oceanic undead are well-suited to their environment. They can move as quickly through the water as they can on land and often carry harpoons and tridents with which to attack their prey, just as they did in life. The seawater filling their bodies also makes them harder to burn, though it is highly conductive to electricity.

Ocean-grafted Ghoul

Octopus Pufferfish - Ocean-grafted Ghoul Token

The creature, a glistening humanoid patterned with pale skin and bright blue rings, inhales a deep breath. Its body briefly inflates, pointing the sharp spines that cover its torso outwards. It drags one arm behind it, the limb splitting into a collection of long, flexing tentacles, while the other ends with a hand of green-tinged claws.

Crab Shark - Ocean-grafted Ghoul Token

A humanoid form lumbers forward. Its muscular body is coated in plates of orange exoskeleton that cover much of the grey, leathery skin. A scarred dorsal fin protrudes from its back, beyond which is a thick tail that resembles a shark’s. The creature drones with a guttural hiss, exposing row upon row of sharpened teeth as it raises a powerful, crab-clawed arm.

A repulsive face of colorless eyes above a maw of thin, misaligned fangs looks slowly back and forth. Each movement flicks the stalk that extends from the monster’s forehead, dangling a glowing bulb. It walks upright, yet its body is long and finned, ending in a tale akin to an eel. Every inch of the creature seems to secrete clear mucus that coats and drips from its skin.

The ocean-grafted ghouls are not truly ghouls, but monstrous, humanoid amalgamations of different ocean denizens. They resemble regular ocean life twisted and combined into the shape of a person, though it is unclear whether they occurred naturally or are the result of strange, magical experimentation. Whatever the reason for their existence, the ghouls are most often found carrying out the commands of sea hags by attacking ships and dragging sailors to their watery graves. This violence and their tendency to consume victims is what earned them the label of ‘ghoul’, as they reminded sailors of stories of bloodthirsty undead monsters.

The three variants provided are only examples of different ocean-grafted ghouls. While the basic ocean-grafted ghoul’s stat block is rather uninteresting, you can use it to create and modify your own ghouls that resemble other sea animals. The actions and abilities you give them could be based on other existing creatures or taken from real-life animals. They should be kept relatively simple to avoid overcomplicating individual versions or drastically affecting their CR value. For example, the animals included in the variants above granted the following, while raising the creatures’ CR values to 1:

  • Crab. Natural armor (+3) and Claw attack.
  • Shark. Pack Tactics and enhanced Bite attack (2d8).
  • Octopus. Underwater Camouflage, Tentacle and Ink spit attacks.
  • Pufferfish. Inflate ability and poisonous Claws attack.
  • Anglerfish. Improved Constitution (12) and Alluring Light ability.
  • Eel. Slick Body ability and Shocking Touch attack.

You can also make an encounter more varied and make your own job easier by featuring ghouls with different combinations from the same selection of animals. With just the six animals given above, and having each ghoul be a combination of two animals, there are fifteen different possibilities!

Balancing the Monsters

To balance the encounter for your party’s level, simply adjust the number of creatures present. The CR 2 sea hag acts as the foundation, with her minions adding to the encounter’s difficulty. Both the seabed zombie and the ocean-grafted ghoul and its variants all have individually low CR values, allowing you to populate the cave with many of them without destabilizing the encounter’s balance. Importantly, remember the impact of action economy and the advantage one side receives from outnumbering the other. You may need to have the creatures attack in divided groups or waves to avoid the party being quickly overwhelmed. The sea hag may call all of her minions at once but they won’t all reach the combat area at the same time.

If you wish to lower the encounter CR for a beginner party, consider omitting the sea hag herself. She may have traveled elsewhere and left behind her minions for the characters to fight in the grotto. This can be used to set up a later conflict with the hag herself, once the party is strong enough.

You can also greatly increase the CR by replacing the singular sea hag with a coven of hags. This should only be done for parties of at least 10th-level or higher if you still plan on littering the cave with minions, as the enemies’ number advantage is further increased and the hags themselves become more powerful. Even if the minions’ CR values reduce them to little more than cannon fodder, they can still overwhelm a higher-level party with their numbers alone.

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Crab Shark - Ocean-grafted Ghoul Token
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About the author

Troy McConnell

Part-time DM and author of 2-Minute Tabletop's encounters, map lore, and characters. Basically, I write about all the campaign ideas that I don't have time to run. All with the assistance of my feline familiar, Wink.

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