Originally posted by Astner
So what I'm wondering is whether there's any actual evidence that contradicts scenes like the one above (and similar scenes) by clarifying beyond any reasonable doubt that he can hold his breath forever?
Do you mean this?
In his early appearances it mentioned many times he can hold his breath indefinitely
More Fun Comics 102
https://ibb.co/k5C9kFG
Superboy 9
https://ibb.co/qybmvNC
As for post X-kryptonite Superman, aside from the scans Abhi posted, I also remember I saw a scan states he can hold his breath indefinitely, but I don't remember the exact book, so I think I need to try search it