Air bubble

Air bubbles are a meter in the Banjo-Kazooie series that show for how much longer Banjo and Kazooie can stay underwater or in other hard-to-breath environments before slowly losing health.

Banjo-Kazooie
In Banjo-Kazooie, Banjo and Kazooie have 6 air bubbles which slowly disappear when underwater. In Clanker's Cavern, a fish named Gloop provides oxygen bubbles for the duo to breath, and they refill one air bubble each.

Banjo-Tooie
In Banjo-Tooie, Banjo and Kazooie retain their 6 air bubbles, but can increase that number to 10 by rescuing and helping Roysten in Spiral Mountain.

Banjo-Kazooie: Grunty's Revenge
In Banjo-Kazooie: Grunty's Revenge, Banjo and Kazooie only have 5 air bubbles. Unlike in previous entries, when Banjo runs out of air, instead of slowly receiving damage, he simply swims back out of the water.