70 Underwater Fantasy Writing Prompts: Sunken Kingdoms, Lost Worlds & Ocean Magic

Underwater fantasy worlds offer some of the most immersive and visually striking settings in the genre. Beneath the surface lies an environment governed by entirely different rules — where light fades into darkness, pressure shapes survival, and entire civilisations may exist hidden from the human world. These settings allow writers to explore not only magical creatures and lost cities, but also the psychological and physical transformation required to exist in such an alien space.

Across literature and mythology, the ocean has long been associated with mystery, danger, and the unknown. From the sirens of ancient Greek myth to the legendary city of Atlantis, underwater worlds often symbolise both beauty and threat. In literary traditions, stories like The Little Mermaid explore the tension between land and sea, identity and transformation, and the cost of crossing between worlds.

In underwater fantasy, the setting is never passive. Currents shift paths, ruins hide forgotten histories, and creatures move through the landscape in ways that challenge human understanding. Characters entering these worlds must adapt — physically, emotionally, and morally — as they encounter forces that are as unpredictable as the ocean itself.

This collection of 70 Underwater Fantasy Writing Prompts is designed as a complete creative toolkit, combining plot hooks, title ideas, opening lines, closing lines, character ideas, setting prompts, and cinematic visual inspiration. These prompts explore themes of transformation, isolation, power, survival, and the tension between two worlds — above and below the surface.

If you would like to explore more immersive fantasy settings, magical worldbuilding ideas, and atmospheric storytelling prompts, you can also browse the Creative Writing Archive or explore the wider Fantasy Writing Hub, where imagined worlds and powerful environments shape every story.

1. Plot Hooks

Underwater fantasy stories often begin with discovery — a descent, a transformation, or the revelation that an entire world exists beneath the surface.

1. Write about a diver who discovers a ruined city that appears to be slowly rebuilding itself.

2. Write about a coastal village where people begin disappearing, only to return changed.

3. Write about a character who can suddenly breathe underwater and doesn’t know why.

4. Write about an explorer who finds a map leading to a kingdom that shouldn’t exist.

5. Write about a royal heir forced to rule a kingdom they have never seen beneath the sea.

6. Write about a scientist who realises the ocean floor is not as empty as believed.

7. Write about a character who hears voices calling them from beneath the water.

8. Write about a submerged civilisation preparing for war with the surface world.

9. Write about a treasure hunter who awakens something ancient in the deep.

10. Write about a character who must choose between returning to land or staying below forever.

2. Title Ideas

Titles for underwater fantasy often suggest mystery, depth, and the tension between beauty and danger.

1. The Kingdom Beneath the Silence

2. Where the Ocean Remembers

3. A Crown of Salt and Stone

4. The City Below the Tide

5. Echoes from the Deep

6. The Last Light Beneath the Waves

7. A Kingdom That Should Not Breathe

8. The Depths That Called My Name

9. Where the Water Hides the Truth

10. The Ocean Never Forgets

3. Opening Lines

Underwater fantasy stories often begin with a moment of unease or wonder — when the familiar world gives way to something deeper and more dangerous.

1. The first time I saw the city beneath the water, I thought I was imagining it.

2. No one believed me when I said the ocean was watching.

3. The map led to a place that didn’t exist on any surface chart.

4. I wasn’t supposed to survive the dive.

5. Something moved beneath the surface long before I entered the water.

6. They told me the sea kept its secrets, but I didn’t realise it also chose who could find them.

7. The deeper I went, the less I recognised the world I had left behind.

8. I heard my name long before I reached the shore.

9. The ocean had always been silent — until it spoke.

10. I should have turned back when the light disappeared.

4. Closing Lines

Underwater fantasy rarely ends with complete resolution. The ocean keeps its mysteries, and characters are often changed by what they encounter.

1. Even after I returned to land, I could still feel the ocean pulling at me.

2. The city disappeared again, as though it had never existed.

3. I realised too late that I had never truly left.

4. Some worlds are not meant to be found twice.

5. The ocean closed behind me, taking the truth with it.

6. I understood then that the surface had never been my home.

7. The deeper world continued without me, as it always had.

8. I had come searching for answers and found something far more dangerous.

9. The tide erased every trace of what had happened.

10. Some stories are meant to remain beneath the surface.

5. Character Ideas

Characters in underwater fantasy often exist between worlds or have been shaped by the demands of an environment that is both beautiful and hostile.

1. A ruler of an underwater kingdom struggling to maintain control over rival factions.

2. A human who has been transformed to survive beneath the sea.

3. A messenger who travels between the surface and the deep.

4. A creature tasked with guarding an ancient ruin.

5. A scientist obsessed with proving the existence of underwater life.

6. A member of a royal court hiding a secret about the origins of their kingdom.

7. A guide who leads outsiders into the ocean for a price.

8. A warrior preparing for a conflict between land and sea.

9. A historian preserving the memory of a civilisation long forgotten.

10. A character who feels more at home underwater than on land.

6. Setting Ideas

Underwater fantasy settings are defined by their physical and sensory differences from the surface world, shaping how characters move, communicate, and survive.

1. A glowing underwater city built from coral and glass.

2. A sunken ruin filled with relics from a lost civilisation.

3. A deep ocean trench where light never reaches.

4. A hidden kingdom protected by powerful currents.

5. A submerged palace carved into rock formations.

6. A coastline where the boundary between land and sea is unstable.

7. A network of underwater caves used as secret passageways.

8. A marketplace where rare objects from both worlds are traded.

9. A battlefield hidden beneath shifting tides.

10. A forgotten temple buried beneath centuries of sand.

7. Picture Prompts

Visual prompts are especially powerful for underwater fantasy because the environment itself creates atmosphere, mystery, and scale. Images of submerged ruins, glowing cities, or solitary figures beneath the ocean encourage writers to imagine stories shaped by isolation, transformation, and the unknown.

Go Deeper into Underwater Fantasy Worlds

To develop underwater fantasy stories, writers can focus on how environment shapes both character and conflict. The ocean is not just a setting but a force that influences every decision, movement, and interaction.

◆ Rewrite a prompt from the perspective of a character who belongs to the underwater world.
◆ Write a scene where a character must adapt to surviving beneath the surface.
◆ Explore how communication works in a world without spoken language.
◆ Describe a moment when a character must choose between two worlds.

Final Thoughts

Underwater fantasy offers a unique approach to worldbuilding, combining beauty, danger, and isolation within a setting that challenges both characters and readers. These worlds are shaped by forces that cannot be controlled, where survival depends on adaptation and understanding rather than dominance.

These 70 Underwater Fantasy Writing Prompts invite writers to explore submerged kingdoms, hidden histories, and the tension between the known and the unknown. Whether used for creative writing exercises, classroom activities, or longer fiction projects, these prompts encourage the creation of immersive worlds where every detail — from light to movement — shapes the story.

If you would like to explore more fantasy settings, imaginative writing prompts, and worldbuilding ideas, you can browse the Creative Writing Archive or visit the Fantasy Writing Hub, where new worlds and storytelling possibilities continue to expand.

Choose Your Next Adventure