Bubbles In Guinness Go Down   As a matter of fact most bubbles do move upwards. The bubbles in the center of the glass, free from the effects of the wall, move upwards most quickly and drag liquid with them. But the liquid moving up in the center of the glass, having nowhere else to go, must eventually turn towards the walls and start to move downward. The liquid moving downward near the walls tries to drag down bubbles with it. Larger bubbles have sufficient buoyancy to resist but smaller bubbles (less than 0.05 mm) are continuously dragged to the bottom of the glass. Flow paths of the bubbles The Red path is the path of the small bubbles The Yellow path is the path of the large bubbles In other beers the bubbles go straight up getting bigger as they reach the surface because the pressure is decreasing .