





UnderDaSea is a mod aiming to upgrade the existing oceans and more by adding more progression for the player as well as new mobs and biodiversity.
[ COMPATIBLE WITH ENCHANTMENT DESCRIPTION AND JUST ENOUGH EFFECT DESCRIPTIONS ] YOU NEED TO INSTALL GECKOLIB AND JEI IS HIGHLY ADVISED
[ IN 2 LANGUAGES: FRENCH AND ENGLISH ]
It adds 4 new biomes.
The Jungle Swamp
The Jungle Swamp is a mix of the swamp and jungle biome. Two specifics mobs spawn there: The pirhana and the firefly.

The Deep Dark Ocean
The Deep Dark Ocean is a variation of the ocean but darker, more gloomy. In this ocean full of sculk like blocks, you will find an horrifying creature named the Sea Lamp Fish. However, this biome keep some good treasures. Who knows, maybe the lampfish keep the key to this treasure ?

The Dead Ocean
The Dead Ocean is not somewhere you want to swim. Dead plants, toxic creatures, dangerous blocks. Who knows what happened here? There's even that little fella named the Red Fish with its cute 3 eyes... How cute!
Just a thing... You might explode!

The Thunder Ocean
The most dangerous biome of the mod. In this biome, cursed with lightening, you can get strike by any minutes. While you need to take precautions, you will find some cool oil rigs like structures and very cool stuff in it. In this biome, lightening can be a good material. In addition, these lightening could give you a curse, or a benediction...
(Note: This is a pre-alpha version, in the release, there are not that many towers in the biome)
It adds also new underwater creatures such as jellyfishes in 3 different sizes, sword fishes, piranhas, red fishes, ray manta, blob fishes, eels and more to come.

It adds new biodiversity such as sea orchins, starfishes, new underwater plants...
5 new discs.
The Fish Net.
The fish net is a net you put underwater. It catches fish, trash and even treasures! You can upgrade your net with some upgrades such as the Lapis-Lazuli Upgrade, the Gold Upgrade, the Diamond and more.
You can also upgrade the fish net with a block of netherite. You can fish faster, more fishes with more upgrades.
New underwater nature such as: starfishes, orchins, corals.
Overall of some vanilla mechanics:
--- The Elder Guardian:
The elder guardian now drops a heart, usable to craft some epic items!
The elder guardian has now 2 phases. When entering the second phase, at 25% of its lives, it will summon lot of guardians to protect itself.
--- The beaches
Did the beaches seemed empty? Welcome the palm trees, snake burrows and the beach rocks!
--- Squid Tentacles
Yummy squid can now be eaten.
Not convinced yet?
Download the mod and test it for youself :)
- Edition: Minecraft Java
- File type: .jar
- Minecraft version listed: 1.20.1
- How to install: Install the matching mod loader (Forge, Fabric or NeoForge) for your Minecraft version. → Download the .jar. → Put it in the .minecraft/mods folder and launch that loader profile.
- Where to get it: Opens on Modrinth — not every file is mirrored on our own servers.
Install steps are the general flow for this file type — How to install Minecraft Java mods & modpacks walks through it step by step.
- Ships as underdasea-1.2.3-forge-1.20.1.jar — drop this file into the mods folder
- Download size: 16.8 MB
- Download link checked 31 Aug 2026 — working
These come from our own check of the pack file, not from the source page.