Oxygen Gauge

The Oxygen Gauge is a gauge that appears whenever Link is underwater without a method allowing him to breathe underwater. Oxygen Gauges have taken multiple forms in the series, and thus far, they have only appeared in 3D titles.

and
The first type of Oxygen Gauge appears in and returns in. It appears as a timer below the Magic Meter, counting down until Link's remaining air supply expires. Once the timer runs out, Link drowns, unless he has a Fairy inside a Bottle. Link can spend an unlimited time underwater if equipped with the Zora Tunic in or if in Zora form in.

The Wind Waker
features the swim timer which appears whenever Link enters deep water, appearing as a blue and white orb in the lower right corner of the screen that slowly drains as time passes. As Link is unable to dive underwater, the gauge serves only as a limit to how far he can go from land, likely to prevent him from visiting other islands prematurely. If the gauge depletes, Link will either be returned to land or, if he drowns while on the open sea, he will appear aboard the King of Red Lions close to the nearest island.

Twilight Princess
In, the Oxygen Gauge appears as a blue bar under Link's Heart Containers, looking similar to the Magic Meter. The gauge appears when Link is underwater when using the Iron Boots, unless he is wearing the Zora Armor. Unlike previous games, bottled Fairies are incapable of reviving Link if he drowns.

Skyward Sword
In SS undefined, the Oxygen Gauge appears as a circular meter similar to the Stamina Meter. Using the spin maneuver underwater causes the gauge to deplete faster, and in Hero Mode, it consume twice as much air. Touching a poison gas bubble also depletes the gauge. Unlike previous games, when the gauge is completely empty, Link does not drown instantly; instead, he begins to lose health. By using an Air Potion, the Oxygen Gauge depletes at a slower rate, while the Air Potion + prevents the Oxygen Gauge from depleting entirely.

Breath of the Wild
Though no Oxygen Gauge appears in, the Stamina Wheel functions similarly to the Oxygen Gauge from The Wind Waker, limiting the amount of time that Link can swim in a body of water. Upon fully depleting the Stamina Wheel, Link will sink below the water and take a small amount of damage. He will reappear back at the last area of solid ground he stood on.