Seaweed Siren

This creature’s three singing heads sway atop serpentine necks that extend from a bulbous body split by a wide, toothy mouth. Pungent strands of seaweed cover the creature like slimy hair.

Seaweed Siren CR 13

XP 25,600
CN Large magical beast (aquatic)
Init +2; Senses darkvision 60 ft., low-light vision; Perception +17; Aura cacophony (100 ft., DC 22)


AC 26, touch 11, flat-footed 24 (+2 Dex, +15 natural, –1 size)
hp 184 (16d10+96)
Fort +16, Ref +12, Will +8
Immune mind-affecting effects; Resist fire 10, sonic 10


Speed 30 ft., swim 30 ft.
Melee bite +25 (4d6+15/19–20)
Ranged 3 sonic beams +17 (5d6 sonic)
Space 10 ft.; Reach 5 ft.
Special Attacks staggering gaze, trample (1d10+15, DC 28)
Spell-Like Abilities (CL 16th; concentration +19)

At willshatter (DC 16)
3/daycharm monster (DC 18), quickened confusion (DC 18)
1/daybestow curse (DC 18, ranged touch attack, 30 ft.)


Str 30, Dex 15, Con 22, Int 11, Wis 16, Cha 19
Base Atk +16; CMB +27; CMD 39 (47 vs. trip)
Feats Blind-Fight, Critical Focus, Deafening Critical, Improved Critical (bite), Point-Blank Shot, Power Attack, Quicken Spell-Like Ability (confusion), Skill Focus (Perception)
Skills Bluff +12, Perception +17, Stealth +17 (+21 in water), Swim +18; Racial Modifiers +4 Stealth in water
Languages Aklo; tongues
SQ false heads, water dependency


Cacophony (Su)

A seaweed siren’s noises disrupt spellcasting; casting within 100 feet of a seaweed siren requires a concentration check (DC 15 + the level of the spell being cast). All other concentration checks and Perception checks involving hearing made inside the aura have their DCs increased by 5. A siren can begin or end this ability as a free action. This is a sonic effect.

False Heads (Ex)

A seaweed siren’s false heads can be severed. To sever a head, an opponent must make a sunder attempt with a slashing weapon targeting the head. A head is considered a separate weapon with hardness 0 and hit points equal to the siren’s Hit Dice (typically 16 hp). To sever a head, an opponent must deal enough damage to reduce the head’s hit points to 0 or fewer. Severing a head deals an amount of damage to the siren’s body equal to the siren’s Hit Dice. A siren can’t attack with a severed head. A siren with no remaining heads can’t use its cacophony ability or its spell-like abilities.

Sonic Beams (Su)

Each of the siren’s false heads can fire a beam at a range of 60 feet, dealing 4d6 points of sonic damage.

Staggering Gaze (Su)

Staggered 1d6 rounds, 30 feet, Will DC 22 negates. This is a mind-affecting effect. The save DC is Charisma-based.

Water Dependency (Ex)

A seaweed siren can survive out of the water for 1 hour per point of Constitution (typically 22 rounds). Beyond this limit, a seaweed siren begins to suffocate.


Environment any coastlines
Organization solitary
Treasure standard

On first glance, this creature appears to blur the line between plant and animal. Three eyeless heads sway above the central body mass, constantly singing, chanting, and speaking in nonsense languages and simple babble.

Seaweed covers the creature’s three false heads and its main central body—a form of camouflage to help the beast remain hidden while hunting. Six stout, crablike legs carry this creature along the coast and through the rocky tide pools it inhabits.

A seaweed siren stands over 8 feet tall from the tip of its stubby legs to the top of its heads, and is nearly 7 feet in diameter. The creature weighs upward of 3,500 pounds.


Seaweed sirens hunt near the shore, where they wait for clam diggers strolling the beaches, lone fisherfolk, or even passing ships. Once a seaweed siren spots its prey, the creature lurks just under the water and allows its three strange heads to protrude above the surface.

The swaying heads sing songs and babble in strange nonsense languages to fuel the seaweed siren’s many special abilities. Even when not in use against a potential meal, the heads seemingly converse with each other, holding lengthy conversations full of random syllables and made-up words. Once it draws its prey near, the seaweed siren attempts to charm or bewilder its foe to gain the advantage. After this, the creature moves closer and begins to devour its still-living victim. While the seaweed siren prefers to dine on living humanoids, it uses its strident squall attacks to incapacitate or kill prey that flees or resists its charm attempts.

Seaweed sirens use a form of aggressive mimicry, appearing to have humanoid features in order to lure in their preferred meals. A seaweed siren’s heads are nothing more than appendages. While they have mouths the creature can breathe through, it doesn’t eat using these mouths. Seaweed sirens’ heads grow differently depending on where the creature developed in order to match the skin tone and apparent ethnicity of the surrounding humanoid population. In addition, the heads are eyeless—the siren sees using the many eyes on its main body mass. A seaweed siren’s eyes twist and spin within their sockets when the creature uses its terrible gaze attack.

When seaweed sirens can’t find their favored food—intelligent creatures and humanoids—they can subsist on fish, but they prefer aquatic mammals as an alternative.

Seals and sea otters find their way into a seaweed siren’s mouth most often, but the creature must actively hunt those morsels, as its particular bait is ineffective against the animals and more likely to scare them off than to lure them closer.

Some sailors report larger and more dangerous variations of the seaweed siren. If these reports are true, some seaweed sirens measure twice the size of regular ones, and possess more than three heads and more powerful abilities.

Habitat & Society

Seaweed sirens live solitary lives, rarely if ever encountering others of their kind. It’s unclear to scholars how these creatures procreate, but they must have some method, since they’ve been spotted along Golarion’s coasts for thousands of years. Some who research the strange monsters pose the theory that seaweed sirens birth their young from thick leathery shells, much like turtle eggs or fibrous seeds.

Seaweed sirens sometimes ally themselves with other aquatic creatures to share in hunts or for mutual protection. Sahuagin typically don’t trust the seaweed sirens, nor do they have the patience to work too closely with the creatures for long, but they have been known to befriend a seaweed siren and work with it long enough to capture new slaves and restock their humanoid food supply.

Locathah sometimes use these strange beasts as protectors, keeping the seaweed sirens well fed in return for the creatures serving as lookouts and sentinels. Merfolk and aquatic elves avoid seaweed sirens, and even go so far as to sometimes warn other humanoid communities when one is discovered to be hunting nearby.

A seaweed siren can speak Aklo, and constantly babbles in glossolalia, but if it manages to talk with another sentient being that has a language long enough, it begins mimicking the other’s language and speech patterns, eventually sounding exactly like it. Though a seaweed siren can use its tongues spell to understand and speak any language, it prefers to talk with and mimic its conversational partners without resorting to using this ability. Some speculate the creature catalogs every conversation in order to add to the collection of sounds and words that power its cacophony special ability.

Section 15: Copyright Notice

Pathfinder Roleplaying Game Bestiary 4 © 2013, Paizo Publishing, LLC; Authors: Dennis Baker, Jesse Benner, Savannah Broadway, Ross Byers, Adam Daigle, Tim Hitchcock, Tracy Hurley, James Jacobs, Matt James, Rob McCreary, Jason Nelson, Tom Phillips, Stephen Radney-MacFarland, Sean K Reynolds, F. Wesley Schneider, Tork Shaw, and Russ Taylor.

Ecology from Pathfinder Adventure Path #60: From Hell’s Heart © 2012, Paizo Publishing, LLC; Authors: Jason Nelson and Rob McCreary.

scroll to top