Air bubble

Oxygen is used in the Banjo-Kazooie series to show how long Banjo and Kazooie can hold their breath underwater. In Banjo-Kazooie, the oxygen meter is shaped like honeycombs. In Banjo-Tooie and Banjo-Kazooie: Grunty's Revenge, the oxygen meter is shaped as bubbles. If Banjo and Kazooie run out of air while underwater, they will drown. If they run out of air in the presence of polluted air or water, they will take constant damage.

In Banjo-Kazooie, Gloop, the fish who is located at the very bottom of Clanker's Cavern, is able to give Banjo and Kazooie air bubbles. These air bubbles replenish two units of oxygen.

In Banjo-Tooie, if Banjo and Kazooie rescue Roysten from under the boulder in Spiral Mountain, he will reward them with four extra Oxygen Bubbles.