With skin overlays enabled:

With skin overlays disabled:

Will take a look at it. Thank you.

In v1.2.0 all models should render correctly.

Hello again!
This is close to being perfect - just a few tweaks needed:

I think this has something to do with the arms moving ("breathing"), like when you stand still.

I can't seem to recreate your issue.
What version of my mod did you use? Maybe it's another mod you are playing with?

I was about to say that I don't play with mods which alter the player model in any way, and I thought I was right. After testing though, I've identified Quark causing this error, but I don't really know why they alter the default player model.

I've opened an issue on their end, because Better Diving works just fine without Quark.