Breath meter

The **breath meter** appears when a player's head is under either water or honey, representing the time the player has until they begin drowning. The breath meter consists of 10 (  ) / 5 ( ) air bubbles (one shown on the right) which fade and disappear gradually as long as the character's head is submerged. When the breath meter is depleted, the player begins to drown and health is lost. The breath meter refills in 1.12 seconds (from zero breath; quicker when more is left, e.g. 0.56 seconds from half breath) as soon as the player emerges from liquid.

For breathing purposes, the player is considered "under water" when the pixel right above their eye is under water. This roughly correlates to just a pixel above where the water will be if the player stands in two full tiles of water with a tile of air in the third tile they occupy. Half-blocks can leave players drowning. In older versions and the Old-gen console version, this was actually the very top pixel of the head. It was changed to prevent players from drowning when their head bumped water-filled blocks.

If a Fish Bowl is worn in the equipment slot, the breath meter appears because the player's head is technically underwater. Breathing equipment and potions can still be used to counter this effect. The lava timer from the Lava Charm and other lava protection gear actually overrides the breath meter visually. This means that if the player's head is in water and the feet are in lava, you can drown without seeing the breath meter.

## Breathing time

The breath meter's duration changes depending on which breathing equipment or potions are used. Times shown below are in real-world time (not game time).

* Without any equipment, the breath meter lasts for 23.33 seconds.
* With a Breathing Reed, breathing time is doubled to 46.67 seconds.
* While wearing diving equipment, the breath meter lasts 93.33 seconds, i.e. 1 minute and 33.33 seconds.
* When both the Breathing Reed and diving equipment are used, the breath meter lasts 186.67 seconds, i.e. 3 minutes and 6.67 seconds.
* Neptune's Shell and its upgrades — Moon Shell and Celestial Shell — eliminate the breath meter while underwater, making breathing time unlimited.
* The Gills Potion eliminates the breath meter while underwater for the length of the buff (2 minutes in total).

### Technical explanation

Every player in *Terraria* bears two attributes called ``breath`` and ``breathCD``. ``breath`` is initially (i.e, upon every spawn) set to a constant value of 200 and ``breathCD`` to 0. When the player is detected to be submerged in water or honey and neither the Gills buff nor the Merfolk buff is active/applicable, ``breathCD`` is incremented by 1. This happens every tick and as soon as ``breathCD`` surpasses a certain ``limit``, **`breathCD`** is reset to 0 and `**breath**` is reduced by one. The ``limit`` of **`breathCD`** is 7 by default, multiplied by 2 to 14 if a Breathing Reed is held and further multiplied by 4 to 28 or 56 if diving equipment is equipped (also checked and updated every tick). As soon as ``breathCD`` hits the ``limit``, ``breath`` is decremented by 1. This is repeated until ``breath`` reaches 0, at which point the player starts drowning. In result, it takes ``breath * limit`` ticks until ``breath`` reaches 0.

## References

1. ↑ A tick is a time unit countable by the software. Most of *Terraria*'s updating logic happens every tick. A tick has the length of 1/60th of a second, hence there are 60 ticks in a second and 3600 ticks in a minute.
2. ↑ Information taken from the PC 1.3.5.3 source code, method `CheckDrowning()` in `Terraria.Player.cs`. There may be inaccuracies, as the current  PC version is 1.4.4.9.

## History

PC version
* Desktop 1.3.5.2: Fixed breath meter moving unexpectedly when using Binoculars, Sniper Scope, or zoom.

* Desktop 1.3.0.1: Moved to above the player's head, from under the Minimap.

* Desktop 1.2: Lava no longer activates the breath meter, allowing players using Obsidian Skin potions or other means to survive under it indefinitely.