The bubbles in the Screenshot are not In-Game. This shot is from the November Press Kit of Silent Hunter 4, you can see that here:
http://www.marinesims.de/site/silent...r-4/sh4-3.html
So most of the screen is really in the game, including Post-Processing Filters. But there are no "bubbles" like that.
But you will see algae if you are on periscope depth (yes i actually played the game) swimming around you...also as the new sea floor with stones and botanical.
Something of this you can see here:
