>>323999227
I was going to use Hirabiki's swimming prefab to make a diving autism world based around exploring a cave but never got around to it. With some decent design it could be good on it's own after adding some air tanks that can be used to refil your air supply mid-dive, but I was going to add a hard mode that included DCI and silt-ups to cater to diving 'tism. 
Had to give up on it due to lack of time