20 Things to Find in a Sea Cave

Adventurers are always investigating remote and isolated sea caves in search of ancient shrines and sunken treasures.


By Matt Morrow (from Fane of the Undying Sleeper)


Such places are rarely devoid of any interesting features, but not all hold the locale of the PCs’ next adventure. Use the table below, to add minor points of interest to your PCs’ adventures in such locales:

  1. A thick line of seaweed—rife with hundreds of tiny crabs—marks the high tide mark. The tangy smell of salt hangs thickly in the air.
  2. Flotsam and jetsam bobs in the water, bumping against the slick cave walls.
  3. Deep rock pools dot the cave’s foreshore. Surprisingly large crabs lurk within.
  4. The cold remains of a small campfire stand upon a high, stony promontory.
  5. A battered rowboat—its mooring line floating nearby—bobs in the water near the cave mouth. Of its occupants, there is no sign, but congealed blood covers the only oar still in the boat.
  6. A ledge high up on one wall holds a multitude of burnt, melted candles. The rock above is blackened with soot.
  7. A precarious tower of single stones piled one on top of another stands upon a prominent rock overlooking the water. The slightest touch causes it to collapse.
  8. A small cairn toward the back of the caverns protects the body of a fallen adventurer. Explorers digging through the cairn discover scraps of bone and rotting or rusted equipment.
  9. Oval, black barnacles grow in profussion below the waterline of the cave. Most seem normal, but a few have odd purple flecks upon their surface.
  10. The cave is bereft of seaweed, except for one corner where someone or something has creates a great mound of the stuff. Within, swarms of tiny crabs lair.
  11. A small passageway leads away from the cave mouth. Perceptive PCs (DC 15 Perception reveals) notice signs the ceiling has been at least partially worked. The passageway comes to an aburpt halt after about 30 ft.
  12. Bizarrely, the shattered curve of part of a stone archway is visible in the water at low tide. Of the rest of the arch, their is no sign.
  13. Small fish swarm in the waters within this cave. Survival checks made here to get along in the wild gain a +2 circumstance bonus.
  14. The cave’s mouth is wide, but low. Within, the cavern roof is much higher, but its low mouth makes entering the cave several hours either side of high tide impossible without a short underwater swim.
  15. At the rear of the cave, a small stream of freshwater trickles out of a narrow fissure in the rock.
  16. A rockfall fills one corner of the cave. It looks unstable, even to the untrained eye. The next storm will carry away several boulders at its base, causing the rest to collapse. Beyond, lies a previously unknown and unexplored passageway.
  17. Remnants of carven stone steps rise out of the water. Several of the lower steps have been all but worn away by the remorseless tides and slick green slime covers much of the remaining stonework.
  18. Incongrously, a large sodden branch still bedecked with many leaves bobs in the water.
  19. This cave is, or was, something of a lover’s grotto. Graffiti scratched into the walls proclaims many couple’s undying love for one another.
  20. The rock around this sea cave’s mouth is covered by lush vegatation that hangs down and obscure the entrance (DC 15 Perception notices). Within, a pile of large stones serves as a small altar. Crude holy symbols daub the walls and various esoteric sigils (drawn with various different coloured chalk) complete the decorations. The air here is noticably colder than normal.  

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20Front_#4_220This article appears in  20 Things #4: Smuggler’s Lair, which is available now. It will also appear in GM’s Miscellany: 20 Things II, available in March 2017.

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4 thoughts on “20 Things to Find in a Sea Cave

    • That’s exactly why I write them, so I’m happy you use them in the same way!

      (The last three articles have all come about directly from my Shattered Star campaign, as I like to combine work and pleasure, but if you’ve got any suggestions for subjects just let me know).