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This mod adds underwater temples/pyramids with some valuable blocks, and funny looking mobs that try and keep you away.

The git repo and download are for the stampy_game, where this mod is pulled from. If you want to use the mod in Minetest_Game you'll need to copy the oceans mod to your mods folder. You'll also need to copy the Sponges mod, as that is a hard dependency. If you already have a different sponges mod, and you want to use it, you'll need to change a bit of code. Open room.lua and change "sponge:sponge_wet" to "sponge:soggy_sponge" in line 43.

More mods by this modder

It doesn't look like I've reviewed any other mods by this author, feel free to suggest one.