When I stand below a water pool whose bottom is closed with any block, preventing the water passage, even without any contact with the water, the underwater effect is displayed. In survival mode it don't detect that you're inside water because you don't lose air, but the effect is displayed similarly.
This doesn't affect any other versions.
EDIT: As stated below, doesn't happens when over 2 blocks below.
Steps to reproduce:
1- Make a pool of any size in a way that you can stand under it.
2- Close the bottom with any block.
3- Stand under it.
4- Your vision become like when you're underwater, even with any contact with water.