While swimming just below the surface the display stopped painting the underwater scenery as 'under water'. The rendering of the underwater surfaces was just as if the water was not present. The water surface was painted as a simple wide (15-20 pixels) line. I was able to move around at this level with the display painting this way. Once I 'surfaced' the rendering switched back to what it shold have been.

I also noticed at several times I was 'under water' and the breath bar did not activate. I went deeper and the bar did not display. After jumping and swimming again, the bar appeared.

Graphics card: NVidia GTX 460M DirectX 11

Hope this helps.