When player 2 loads into the map, the water looks different. The color is different and opaque. You cannot see through it at all, it does not allow the light from sea pickles to pass through, nor can you see fish swimming in lakes, rivers, etc.. 

We have tried to see if there is a difference when loading our map with different texture packs, loading different maps all together, and signing in with different accounts, but the problem still persists.