Faentum's Deep Sea Expansion
by Faentum
Faentum's Deep Sea Expansion adds a hostile abyssal boss, a deep-sea eel and a harmless glowing octopus to the ocean floor beyond the coral reefs and shipwrecks.
What it does
Far below the surface, past coral reefs and shipwrecks, the mod fills the deep ocean with new mobs. The Abyssal Leviathan is a massive, glowing boss that rarely appears, so meeting it feels like a real discovery. Surviving the encounter earns Varuna's Trident, an artifact that grants Water Breathing and Water Walking.
Smaller mobs share the depths as well. The Deep Sea Moray is an elusive giant eel that slides across the ocean floor, blends into shadow and can startle a diver with a sudden appearance. The octopus is passive and emits a soft glow that lights dark water. The server and every player need the mod installed. Files exist for Forge and NeoForge, for 1.20.1 and 1.20.4, and it requires Geckolib.
Key features
Abyssal Leviathan boss
A large glowing ocean boss that spawns rarely, with a fight that rewards survival in the deep.
Varuna's Trident
A reward from defeating the Leviathan that grants Water Breathing and Water Walking.
Deep Sea Moray
A hostile giant eel that lurks in the dark and uses bioluminescence to attack when players come too close.
Glowing octopus
The octopus is a small, harmless creature that floats through the deep, and its body gives off a soft glow that helps light up dark water.
Gallery
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 1
Use cases
Deep ocean exploration
Players who travel past the reefs and wrecks meet new mobs on the seafloor and in the dark water below.
Ocean boss encounters
Players who want a rare, large ocean fight can search the depths for the Leviathan.
Who it’s for: Players who explore the ocean and want more danger in the deep water, and servers that want a harder ocean biome.
How it compares
In the depths is a Forge and NeoForge mod for 1.20.1 – 1.21.1, released under the MIT License and not open source, and it runs on client and server. Reaper Leviathan is NeoForge only, published for 1.21.4 under the CC0 1.0 Universal license. Ocean Giants is server-side only, so players join without installing it, and it covers 1.21.1 – 1.21.11 on Forge and NeoForge.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Faentum's Deep Sea Expansion | Forge and NeoForge | 1.20.1 – 1.20.4 | Client and server | 2026-07-04 |
| In the depths | Forge and NeoForge | 1.20.1 – 1.21.1 | Client and server | 2024-12-04 |
| Reaper Leviathan | NeoForge | 1.21.4 | Client and server | 2025-06-08 |
| Ocean Giants | Forge and NeoForge | 1.21.1 – 1.21.11 | Server-side only | 2026-07-18 |
Questions
Does Faentum's Deep Sea Expansion need Geckolib?
Does the server need the mod?
Which game versions does the mod support?
In the catalog
Faentum's Deep Sea Expansion is one of 11,058 Mobs mods on ModsFinder, and one of 6,527 Mobs mods for Forge. 13,907 mods support Minecraft 1.20.4.
More from Faentum
Similar mods
What the author says
The oceans of Minecraft have always felt a little too safe. Far below the surface, beyond the coral reefs and shipwrecks, something ancient roams the depths. The deep ocean is no longer empty—it is alive, glowing, and dangerous.
Official listing
- Modrinth page
- modrinth.com/mod/fdse
- Owner
- Faentum
- Published
- 2026-05-26
- Updated on Modrinth
- 2026-07-04
- Facts verified
- 2026-10-15