Full credits to dannytaylor, who created the datapack, and to judgealexander for the original idea.
The photos show it alongside mods from the list; the datapack on its own does not generate any kind of island or any non vanilla structures.
Minecraft's biomes are not removed or replaced: all of them, including the ones that would normally be terrestrial — such as plains, forests, desert, or jungle — still generate, just submerged now. This means structures associated with those biomes (villages, temples, pyramids, mansions, or ones from mods/other datapacks) also keep generating normally.
In addition, the seafloor of non-oceanic vanilla biomes is lightly enriched with underwater vegetation.
This datapack has only been tested on NeoForge.
It doesn't depend on any mod, but the following are strongly recommended for a better experience:
MAIN
It's designed to coexist with mods that add their own marine or terrestrial biomes and/or structures (tested with everything on the list above, and with many structure mods as well): since the datapack doesn't replace or block the Overworld's biome list, those mods can keep inserting their biomes and structures normally, without conflicts.
Notes
Version for 1.20.1:
I only changed a single number inside the datapack to make it compatible with Minecraft 1.20.1. To visit the original creator, click here.
I recommend using it together with structure and biome mods, since some of these will generate around the world, filling it with life instead of just an empty ocean.
