Put the summary of the bug you're having here

I was doing some survival in the new snapshots Minecraft 14w07a and I decided to make a diving board I ran and jumped in to the water and I noticed that i was not losing air but as soon as I stopped and went to the bottom I started to lose air.

What I expected to happen was...:
In most of the minecraft versions as soon as you hit the water you start to air.

What actually happened was...:
As soon as I hit the water i noticed that i was not losing air as long as i was going up and down but as soon as i stopped moving and hit the bottom i started losing air but i also noticed was when i was moving up and down the air gui was glitching also.

Steps to Reproduce:
Just jump in a deep pool of water
and swim up and down in the water and you will see the you never lose air as long as you are moving