So I found this bug by accident when I was checking Ender Pearls and noticed that you can breathe endlessly
How to see this bug?
It's easy! Just dig into the depth of 10 blocks, then you need to break 11 and put Soulsand, then fill it all with water, and the last step is to put Trapdoor. Everything is ready! If you need more details, watch the video! I hope I helped you, good luck!
While being in Bubble Columns, you don't use up air.