Swim underwater and stay on the bottom. Your air level will decrease. Start swim up and you will see that your air level full again.
I think that water block have little layer of air on top of them.
MC-48564
Underwater breathing without effects
Resolved
Duplicate
0
Duplicate of MC-48395 - If you have not, please use the search function in the future, to see if your bug has already been submitted. If you could not find the original report, please comment with the keywords you searched for.