Windows 10 (Full Minecraft however, not Win 10 edition), Java 8
You can see water perfectly through the water.
What I expected to happen was...:
I expected it to be shaded white like other blocks and mobs are through the edge of a beacon.
What actually happened was...:
You can perfectly see water as if it is in front of the beacon.
Steps to Reproduce:
1. Have water at a distance, or near the beacon.
2. Place a beacon and have it shoot the beam.
3. Look through the edge of the beam towards the water - it will be perfectly visible.
This happens with and without texture packs, and on multiple computers. I had other players on my server test this both on the server and in Single Player.