Snapshots can be found on curseforge
This aims to improve minecraft cave generation through the addition of a few new structures, 6 new ore, and 13 new underground cave biomes, many of which can be combined to form combo caves which can bring the count to above 30 caves.
Different caves can be found at different y levels and some can be found in different biomes.
While making this mod I watched videos featuring ideas for a minecraft cave update. Some ideas have been borrowed from those videos. You will be able to find most of them just by searching up "Cave mod ideas" on youtube