When a person is underwater, they need to retain as much oxygen as possible to stay submerged. However, staying submerged for too long without resurfacing can result in a buildup of carbon dioxide in the blood, leading to poisoning or suffocation. In more severe cases, involuntary inhalation of water can cause drowning.
Holding breath is often depicted with tightly closed lips and puffed-up cheeks. This tag should primarily be used for humans in underwater scenarios, rather than for fantasy creatures like mermaids.
