Help Bob catch as many bubbles as possible. Just click your mouse on the screen to have Bob swim in that direction. The further away you click the further he will swoosh.
You start with 30 seconds on the clock. If you can reach the goal by catching the required number of bubbles before the clock reaches 0, then another 30 seconds is added to the clock and a new goal is set. If you fail to reach the goal by the time the clock reaches 0, the game will end.
To make matters worse, Bob faces several dangers you must help him avoid. There are crabs and falling garbage that take your bubbles away, plus fishermen and sharks that take your life. Though some say that flashing starfish may be helpful to you.