This datapack forces the game to generate no terrain above layer 63.

How does it work ?

Quite simply, it modifies the “continent” generation variable and forces it to have a value between -2.0 and -0.2. This creates a mirror effect above layer 63. Tall mountains become ocean trenches, and plains become shallow oceans.

You can change the minimum value in:

~/Seablock & Lavablock/data/minecraft/worldgen/density_function/overworld/continents.json

With the parameter: “max”: -0.2

/!\ Setting it to -0.1 will generate only ocean biomes, but with normal terrain. Increase this value toward -2.0, and small islands will become rarer or even nonexistent, and the oceans will be deeper.

What gets generated?

All ocean biomes are generated, as well as mushroom plains and rare islands.

Ocean structures are also present (shipwrecks, monuments, ruins, buried chests, etc).

/!\ Due to the specific generation process, ocean biomes are immense because there are ultimately very few of them. However, you can work around this issue with other generation datapacks, as most are compatible with a few exceptions.

But what about the Nether?

Since it was generated differently to begin with, I had to change my approach. So I ended up reducing the “terrain density,” which creates this lava ocean effect with floating islands. In this dimension, all structures and biomes are generated.

And the End?

I didn’t change anything, since it’s already a dimension with an ocean of emptiness and islands.

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I created this datapack for a concept for one of my servers; if you'd like to use it, feel free to do so. If you'd like a version compatible with 26.3 or later, let me know in the comments.

Thanks to everyone who downloads this datapack, and have fun!