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 (approximately one every 10 seconds). In Clanker's Cavern, a fish named Gloop provides oxygen bubbles for the duo to breath, and they refill two air bubbles each. In Rusty Bucket Bay, Banjo and Kazooie lose air at the normal rate while on the surface of the polluted water, and twice as quickly while underwater. This is also the case in the Winter area of Click Clock Wood, due to the water being ice cold.

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.