Air is a feature in mope.io, similar to "oxygen" in other IOgames. If you dive or dig, your air will slowly decrease (speed of decrease will be different depending on your current animal) . When the air bar reaches 1/4 like all other bars, it will make a red flash saying: LOW Air. You can regain air by going on going in whirlpools or hiding holes. If not regained, the animal will automatically stop diving or digging.