Reach the hole/pond with a group of about eight jellyfish. You have to kill at least three jellyfish simultaneously. Get the group to move from left to right and hit the air bubbles. Try to get them on top of each other and when one blows there will be a large air bubble. It will cause a ripple effect if the rest of the jellyfish are close enough. Reload the wave and try again if you did not kill enough. The achievement will be earned at the end of the game.