If you go underwater, and go up under a block, you see, there is air, but if you wait a little bit, then you get damaged. And you see under a block the water brighter than normal.
Screen:
http://i.imgur.com/5t0Jd.png
If you go underwater, and go up under a block, you see, there is air, but if you wait a little bit, then you get damaged. And you see under a block the water brighter than normal.
Screen:
http://i.imgur.com/5t0Jd.png
There's air, but not enough to get to it seems. If the hole was dug behind you a little bit, you'd have enough air to breathe as the water would fall down a bit.